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21 pages, 8295 KiB

Open AccessArticle

Simulation of Surface Settlement Induced by Parallel Mechanised Tunnelling

by Chia Yu Huat, Danial Jahed Armaghani, Sai Hin Lai, Haleh Rasekh and Xuzhen He

Sustainability 2023, 15(17), 13265; https://doi.org/10.3390/su151713265 - 4 Sep 2023

Viewed by 1444

Abstract

Mechanised tunnelling is extensively utilised for twin tunnel construction, particularly in urban areas. A common challenge encountered during this construction method is the occurrence of surface settlement (SS) induced by tunnelling activities. The integrity of nearby structures can be compromised by SS, making [...] Read more.

Mechanised tunnelling is extensively utilised for twin tunnel construction, particularly in urban areas. A common challenge encountered during this construction method is the occurrence of surface settlement (SS) induced by tunnelling activities. The integrity of nearby structures can be compromised by SS, making it imperative to accurately quantify and mitigate this phenomenon. Several methods for determining SS exist, including empirical formulas and laboratory studies. However, these methods are often constrained by specific soil types and are time-consuming. Moreover, crucial parameters such as tunnel operational factors and construction stages are often omitted from empirical formulas. Given these limitations, this paper aims to address these challenges by employing 3D numerical analysis to simulate tunnelling-induced SS in twin tunnels. This approach takes into account tunnel geometry, construction sequencing, soil properties, and tunnelling operational factors. By incorporating data from in-situ and laboratory tests conducted on the ground, engineering soil parameters are established as inputs for the numerical analysis. The simulated SS results obtained from the 3D numerical analysis are compared with field measurements of SS taken from available ground surface settlement markers. The transverse SS pattern derived from the numerical analysis closely mirrors the field measurements. Additionally, SS values above the first and second tunnels are compared with field measurements, resulting in coefficient of determination (R²) values of 0.94 and 0.96, respectively. The utilisation of the 3D numerical modelling approach enables the customizable mitigation strategies for managing the SS with project-specific parameters such as tunnel geometry, geotechnical engineering factors, and tunnelling operational variables. This will help plan and construct more sustainable tunnels with minimal effects on the ground and residential areas. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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22 pages, 3908 KiB

Open AccessArticle

Study on the Impact of Different Parameters on Prediction of Crown Deformations in Underground Caverns

by Kadiyala Sudhakar, Rabindra Kumar Sinha and Sripad Ramachandra Naik

Sustainability 2023, 15(17), 12851; https://doi.org/10.3390/su151712851 - 25 Aug 2023

Cited by 1 | Viewed by 1100

Abstract

Crown deformation is a major concern in the design and construction of underground caverns. It can lead to damage to the cavern structure and surrounding infrastructure and can also pose a safety hazard to workers. This paper studies the factors affecting crown deformation [...] Read more.

Crown deformation is a major concern in the design and construction of underground caverns. It can lead to damage to the cavern structure and surrounding infrastructure and can also pose a safety hazard to workers. This paper studies the factors affecting crown deformation in underground caverns. A parametric study was conducted to investigate the effects of seven parameters on crown deformation: rock mass rating (RMR), uniaxial compressive strength (UCS), Young’s modulus of intact rock (Ei), Poisson’s ratio (υ), tensile strength (σt), angle of internal friction (φ), and cohesion (C). The results of the parametric study showed that the following parameters significantly affected crown deformation: RMR, UCS, Ei, and Φ. A multiple linear regression analysis was conducted to develop a regression equation to predict crown deformation. The coefficient of determination (R²) for the regression equation is 92.92%, which indicates that the equation is a good predictor of crown deformation. The parametric study results and the regression analysis can be used to improve the design and construction of underground caverns. By considering the factors that affect crown deformation, engineers can design more stable caverns that are less likely to experience deformations. The results of the study can be used to improve the design and construction of caverns, making them safer and more sustainable. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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25 pages, 5728 KiB

Open AccessArticle

Molecular Dynamics Simulation of Forsterite and Magnesite Mechanical Properties: Does Mineral Carbonation Reduce Comminution Energy?

by Akash Talapatra and Bahareh Nojabaei

Sustainability 2023, 15(16), 12156; https://doi.org/10.3390/su151612156 - 9 Aug 2023

Viewed by 1204

Abstract

This work compares the mechanical properties of two geomaterials: forsterite and magnesite. Various physical conditions are considered to investigate the evolution of stress–strain relationships for these two polycrystals. A molecular-scale study is performed on three-dimensional models of forsterite and magnesite. Three different temperatures [...] Read more.

This work compares the mechanical properties of two geomaterials: forsterite and magnesite. Various physical conditions are considered to investigate the evolution of stress–strain relationships for these two polycrystals. A molecular-scale study is performed on three-dimensional models of forsterite and magnesite. Three different temperatures (300 K, 500 K, and 700 K) and strain rates (0.001, 0.01, and 0.05 ps⁻¹) are considered to initiate deformation in the polycrystals under tensile and compressive forces. The polycrystalline structures face deformation at lower peaks at high temperatures. The Young’s modulus values of forsterite and magnesite are found to be approximately 154.7451 GPa and 92.84 GPa under tensile forces and these values are found to be around 120.457 GPa (forsterite) and 77.04 GPa (magnesite) for compressive forces. Increasing temperature reduces the maximum strength of the polycrystalline structures, but forsterite shows higher ductility compared to magnesite. Strain rate sensitivity and the effect of grain size are also studied. The yield strengths of the forsterite and magnesite drop by 7.89% and 9.09% when the grain size is reduced by 20% and 15%, respectively. This study also focuses on the changes in elastic properties for different pressures and temperatures. In addition, from the radial distribution function (RDF) results, it was observed that the peak intensity of pairwise interaction of Si–O is higher than that of Mg–O. Finally, it is found that the formation of magnesite, which is the product of mineral carbonation of forsterite, is favorable in terms of mechanical properties for the comminution process. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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18 pages, 23715 KiB

Open AccessArticle

Study on the Dynamic Mechanism of the Desiccation Crack Initiation and Propagation in Red Clay

by Aijun Chen, Chaohua Li, Shanshan Zhao, Bai Yang and Chuanyang Ding

Sustainability 2023, 15(14), 11156; https://doi.org/10.3390/su151411156 - 18 Jul 2023

Cited by 1 | Viewed by 1416

Abstract

Red clay is susceptible to cracking in desiccating environments, with resulting crisscrossing cracks that compromise the soil structure and increase the likelihood of geological hazards. To investigate the dynamic mechanism of the initiation and propagation of soil desiccation cracks under natural hygrothermal conditions, [...] Read more.

Red clay is susceptible to cracking in desiccating environments, with resulting crisscrossing cracks that compromise the soil structure and increase the likelihood of geological hazards. To investigate the dynamic mechanism of the initiation and propagation of soil desiccation cracks under natural hygrothermal conditions, a desiccation test was conducted on a red clay slurry using three-dimensional digital image correlation (3D DIC) technology. The evolution behaviour of desiccation cracks was analysed, and the dynamic relationships between moisture content, displacement field, strain field, and soil desiccation cracking were explored. The test results showed that the Atterberg limits of red clay are correlated with desiccation cracking. Cracks tend to initiate in areas where tensile strain is concentrated or significant displacement differences exist. Following crack initiation, the surrounding strain and displacement fields redistribute, influencing the propagation direction, development rate, and morphology of subsequent cracks nearby. Additionally, the relative displacement and strain at the edges of cracks are related to the crack propagation direction. Earlier crack initiation usually corresponds to a larger relative displacement and strain at the crack edges, while the displacement and strain at the soil clod centre are typically smaller than those at the crack edges. DIC technology can quickly and accurately obtain dynamic information about displacement and strain fields, providing feasible technical support for analysing the dynamic mechanism behind soil desiccation cracking. It has potential value in engineering hazard prevention and sustainable development. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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13 pages, 9140 KiB

Open AccessArticle

Damping of Dry Sand in Resonant Column-Torsional Simple Shear Device

by Majd Ahmad and Richard Ray

Sustainability 2023, 15(14), 11060; https://doi.org/10.3390/su151411060 - 14 Jul 2023

Cited by 1 | Viewed by 1185

Abstract

The damping ratio values of three different Danube sands were measured in the Resonant Column-Torsional Simple Shear device (RC-TOSS). The distinctive configuration of the RC-TOSS device employed in this investigation enabled the performance of both tests using a single sample. This research estimates [...] Read more.

The damping ratio values of three different Danube sands were measured in the Resonant Column-Torsional Simple Shear device (RC-TOSS). The distinctive configuration of the RC-TOSS device employed in this investigation enabled the performance of both tests using a single sample. This research estimates and compares the damping ratio values measured with three distinct methods (two of which are in the RC test): The Free Vibration Decay (FVD), the Steady-State Vibration (SSV) methods, and the method of calculating the damping ratio from the hysteretic loops generated in the TOSS test. Both dense and loose samples were tested up to a peak-to-peak amplitude shear strain of 1%. The device provides measurements over a wide range of shear strain amplitudes. The results support the employment of the SSV methods at low strains (below 0.005%), while the FVD method gives a better estimate at higher strains (above 0.03%). The two methods and the TOSS results are in agreement with each other between 0.005% and 0.03%. The effect of the number of cycles on the damping ratio was investigated where a significant decrease was observed in the damping ratio with an increasing number of cycles. A parameter is introduced to describe the rate of this decrease, which should be considered during the structural design to reduce maintenance and life-cycle costs and enhance sustainability. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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24 pages, 7639 KiB

Open AccessArticle

Appraisal of Different Artificial Intelligence Techniques for the Prediction of Marble Strength

by Muhammad Saqib Jan, Sajjad Hussain, Rida e Zahra, Muhammad Zaka Emad, Naseer Muhammad Khan, Zahid Ur Rehman, Kewang Cao, Saad S. Alarifi, Salim Raza, Saira Sherin and Muhammad Salman

Sustainability 2023, 15(11), 8835; https://doi.org/10.3390/su15118835 - 30 May 2023

Cited by 8 | Viewed by 1771

Abstract

Rock strength, specifically the uniaxial compressive strength (UCS), is a critical parameter mostly used in the effective and sustainable design of tunnels and other engineering structures. This parameter is determined using direct and indirect methods. The direct methods involve acquiring an NX core [...] Read more.

Rock strength, specifically the uniaxial compressive strength (UCS), is a critical parameter mostly used in the effective and sustainable design of tunnels and other engineering structures. This parameter is determined using direct and indirect methods. The direct methods involve acquiring an NX core sample and using sophisticated laboratory procedures to determine UCS. However, the direct methods are time-consuming, expensive, and can yield uncertain results due to the presence of any flaws or discontinuities in the core sample. Therefore, most researchers prefer indirect methods for predicting rock strength. In this study, UCS was predicted using seven different artificial intelligence techniques: Artificial Neural Networks (ANNs), XG Boost Algorithm, Random Forest (RF), Support Vector Machine (SVM), Elastic Net (EN), Lasso, and Ridge models. The input variables used for rock strength prediction were moisture content (MC), P-waves, and rebound number (R). Four performance indicators were used to assess the efficacy of the models: coefficient of determination (R²), Root Mean Square Error (RMSE), Mean Square Error (MSE), and Mean Absolute Error (MAE). The results show that the ANN model had the best performance indicators, with values of 0.9995, 0.2634, 0.0694, and 0.1642 for R², RMSE, MSE, and MAE, respectively. However, the XG Boost algorithm model performance was also excellent and comparable to the ANN model. Therefore, these two models were proposed for predicting UCS effectively. The outcomes of this research provide a theoretical foundation for field professionals in predicting the strength parameters of rock for the effective and sustainable design of engineering structures Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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26 pages, 15345 KiB

Open AccessArticle

Salt Cavern Thermal Damage Evolution Investigation Based on a Hybrid Continuum-Discrete Coupled Modeling

by Kai Feng, Wenjing Li, Xing Nan and Guangzhi Yang

Sustainability 2023, 15(11), 8718; https://doi.org/10.3390/su15118718 - 28 May 2023

Cited by 3 | Viewed by 1699

Abstract

The integrity and stability of salt caverns for natural gas storage are subjected to a gas cycling loading operation. The coupled effect of confining pressure and temperature on the response of the salt cavity surrounding the wall is essential to stability analysis. In [...] Read more.

The integrity and stability of salt caverns for natural gas storage are subjected to a gas cycling loading operation. The coupled effect of confining pressure and temperature on the response of the salt cavity surrounding the wall is essential to stability analysis. In this study, a hybrid continuum-discrete model accounting for the thermal-mechanical process is proposed to investigate the thermal-damage evolution mechanism towards a field case with blocks falling off the salt cavity. The salt cavity is modeled by continuum zones, and the potential damage zones are simulated by discrete particles. Three specimens at different locations around the surrounding wall are compared in the context of severe depressurization. The dynamic responses of rock salt, including temperature spatiotemporal variation, microscopic cracking patterns, and energy evolution exhibit spatial and confinement dependence. A series of numerical simulations were conducted to study the influence of microproperties and thermal properties. It is shown that the evolution of cracks is controlled by (1) the thermal-mechanical process (i.e., depressurization and retention at low pressure) and (2) the anomalous zone close to the brim of the salt cavity surrounding the wall. The zone far away from the marginal surrounding wall is less affected by temperature, and only the mechanical conditions control the development of cracks. This continuum/discontinuum approach provides an alternative method to investigate the progressive thermal damage and its microscopic mechanism. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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20 pages, 3351 KiB

Open AccessArticle

Optimized Data-Driven Models for Prediction of Flyrock due to Blasting in Surface Mines

by Xiaohua Ding, Mehdi Jamei, Mahdi Hasanipanah, Rini Asnida Abdullah and Binh Nguyen Le

Sustainability 2023, 15(10), 8424; https://doi.org/10.3390/su15108424 - 22 May 2023

Cited by 4 | Viewed by 1841

Abstract

Using explosive material to fragment rock masses is a common and economical method in surface mines. Nevertheless, this method can lead to some environmental problems in the surrounding regions. Flyrock is one of the most dangerous effects induced by blasting which needs to [...] Read more.

Using explosive material to fragment rock masses is a common and economical method in surface mines. Nevertheless, this method can lead to some environmental problems in the surrounding regions. Flyrock is one of the most dangerous effects induced by blasting which needs to be estimated to reduce the potential risk of damage. In other words, the minimization of flyrock can lead to sustainability of surroundings environment in blasting sites. To this aim, the present study develops several new hybrid models for predicting flyrock. The proposed models were based on a cascaded forward neural network (CFNN) trained by the Levenberg–Marquardt algorithm (LMA), and also the combination of least squares support vector machine (LSSVM) and three optimization algorithms, i.e., gravitational search algorithm (GSA), whale optimization algorithm (WOA), and artificial bee colony (ABC). To construct the models, a database collected from three granite quarry sites, located in Malaysia, was applied. The prediction values were then checked and evaluated using some statistical criteria. The results revealed that all proposed models were acceptable in predicting the flyrock. Among them, the LSSVM-WOA was a more robust model than the others and predicted the flyrock values with a high degree of accuracy. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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17 pages, 3849 KiB

Open AccessArticle

Infrared Precursor Experiment to Predict Water Inrushes in Underground Spaces Using a Multiparameter Normalization

by Kewang Cao, Furong Dong, Liqiang Ma, Naseer Muhammad Khan, Tariq Feroze, Saad S. Alarifi, Sajjad Hussain and Muhammad Ali

Sustainability 2023, 15(9), 7570; https://doi.org/10.3390/su15097570 - 5 May 2023

Cited by 6 | Viewed by 1372

Abstract

Rock failure is the root cause of geological disasters such as slope failure, civil tunnel collapse, and water inrush in roadways and mines. Accurate and effective monitoring of the loaded rock failure process can provide reliable precursor information for water inrushes in underground [...] Read more.

Rock failure is the root cause of geological disasters such as slope failure, civil tunnel collapse, and water inrush in roadways and mines. Accurate and effective monitoring of the loaded rock failure process can provide reliable precursor information for water inrushes in underground engineering structures such as in mines, civil tunnels, and subways. The water inrush may affect the safe and efficient execution of these engineering structures. Therefore, it is essential to predict the water inrush effectively. In this paper, the water inrush process of the roadway was simulated by laboratory experiments. The multiparameters such as strain energy field and infrared radiation temperature field were normalized based on the normalization algorithm of linear function transformation. On the basis of analyzing the variation characteristics of the original parameters, the evolution characteristics after the parameters normalization algorithm were studied, and the precursor of roadway water inrush was predicted comprehensively. The results show that the dissipation energy ratio, the infrared radiation variation coefficient (IRVC), the average infrared radiation temperature (AIRT), and the variance of successful minor infrared image temperature (VSMIT) are all suitable for the prediction of roadway water inrushes in the developing face of an excavation. The intermediate mutation of the IRVC can be used as an early precursor of roadway water inrush in the face of an excavation that is being developed. The inflection of the dissipation energy ratio from a declining amount to a level value and the mutation of VSMIT during rock failure can be used as the middle precursor of roadway water inrush. The mutation of AIRT and VSMIT after rock failure can be used as the precursor of roadway imminent water inrush. Combining with the early precursor and middle precursor of roadway water inrush, the graded warning of “early precursor–middle precursor–final precursor” of roadway water inrush can be obtained. The research results provide a theoretical basis for water inrush monitoring and early warning in the sustainable development of mine, tunnel, shaft, and foundation pit excavations. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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14 pages, 5716 KiB

Open AccessArticle

Scale Effects on Shear Strength of Rough Rock Joints Caused by Normal Stress Conditions

by Jiayi Shen, Chenhao Sun, Huajie Huang, Jiawang Chen and Chuangzhou Wu

Sustainability 2023, 15(9), 7520; https://doi.org/10.3390/su15097520 - 4 May 2023

Cited by 1 | Viewed by 1622

Abstract

Scale effects on the mechanical behavior of rock joints have been extensively studied in rocks and rock-like materials. However, limited attention has been paid to understanding scale effects on the shear strength of rock joints in relation to normal stress σ_n applied [...] Read more.

Scale effects on the mechanical behavior of rock joints have been extensively studied in rocks and rock-like materials. However, limited attention has been paid to understanding scale effects on the shear strength of rock joints in relation to normal stress σ_n applied to rock samples under direct shear tests. In this research, a two-dimensional particle flow code (PFC2D) is adopted to build a synthetic sandstone rock model with a standard joint roughness coefficient (JRC) profile. The manufactured rock model, which is adjusted by the experiment data and tested by the empirical Barton’s shear strength criterion, is then used to research scale effects on the shear strength of rock joints caused by normal stresses. It is found that the failure type can be affected by JRC and σ_n. Therefore, a scale effect index (SEI) that is equal to JRC plus two times σ_n (MPa) is proposed to identify the types of shear failure. Overall, shearing off asperities is the main failure mechanism for rock samples with SEI > 14, which leads to negative scale effects. It is also found that the degree of scale effects on the shear strength of rock joints is more obvious at low normal stress conditions, where σ_n < 2 MPa. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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25 pages, 11219 KiB

Open AccessArticle

Slope Failure Risk Assessment Considering Both the Randomness of Groundwater Level and Soil Shear Strength Parameters

by Pu Peng, Ze Li, Xiaoyan Zhang, Wenlian Liu, Sugang Sui and Hanhua Xu

Sustainability 2023, 15(9), 7464; https://doi.org/10.3390/su15097464 - 1 May 2023

Cited by 3 | Viewed by 1752

Abstract

Conducting research on slope failure risk assessment is beneficial for the sustainable development of slopes. There will be various failure modes considering both the randomness of the groundwater level and soil shear strength parameters. Based on the integrated failure probability (IFP), [...] Read more.

Conducting research on slope failure risk assessment is beneficial for the sustainable development of slopes. There will be various failure modes considering both the randomness of the groundwater level and soil shear strength parameters. Based on the integrated failure probability (IFP), the traditional failure risk analysis needs to count all failure modes, including the failure probability (P_f) and failure risk coefficient (C), one-by-one. A new slope failure risk assessment method that uses the sum of the element failure risk to calculate the overall failure risk is proposed in this paper and considers both the randomness of the groundwater level and soil shear strength parameters. The element failure probability is determined by their location information and failure situation; the element failure risk coefficient is determined by their area. It transforms the complex overall failure risk problem into a simple element failure risk problem, which simplifies the calculation process and improves the calculation efficiency greatly. The correctness is verified with the systematic analysis of a classical case. The results show that the slope failure probability and failure risk are greatly increased from 1.40% to 3.30% and 0.829 m² to 2.094 m² with rising groundwater level, respectively. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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14 pages, 4000 KiB

Open AccessArticle

Estimation of Modulus of Deformation Using Rock Mass Rating—A Review and Validation Using 3D Numerical Modelling

by Hema Vijay Sekar Bellapu, Rabindra Kumar Sinha and Sripad Ramchandra Naik

Sustainability 2023, 15(7), 5721; https://doi.org/10.3390/su15075721 - 24 Mar 2023

Cited by 1 | Viewed by 1559

Abstract

The Himalayan region has enormous potential for hydropower development. However, variations in geological and geotechnical conditions pose challenging tasks for the designers. If these variations are not tackled in a timely manner during underground excavations, especially for caverns, instabilities may occur, resulting in [...] Read more.

The Himalayan region has enormous potential for hydropower development. However, variations in geological and geotechnical conditions pose challenging tasks for the designers. If these variations are not tackled in a timely manner during underground excavations, especially for caverns, instabilities may occur, resulting in time and cost over-runs. For sustainable hydropower development, minimizing these over-runs is necessary. The modulus of deformation (E_d) of a rock mass is an essential input parameter required in the design of underground excavations. This study involves collecting the results of extensive in situ tested values for various hydroelectric projects in the Himalayan regions, along with the rock mass rating (RMR) values at 35 test sites. E_d is estimated empirically based on statistical analysis. Comparisons were made with the empirical equations already available in the literature, using RMR and the proposed equation for estimating E_d. Although different researchers have proposed many equations for estimating the value of E_d using RMR, a gap exists in validating such equations. In this regard, the proposed equation for E_d was verified by carrying out 3D numerical-modelling studies using FLAC3D, an explicit finite-difference software for an underground powerhouse cavern and comparing the displacement values with the field instrumentation data. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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22 pages, 6414 KiB

Open AccessArticle

Performance of Statistical and Intelligent Methods in Estimating Rock Compressive Strength

by Xuesong Zhang, Farag M. A. Altalbawy, Tahani A. S. Gasmalla, Ali Hussein Demin Al-Khafaji, Amin Iraji, Rahmad B. Y. Syah and Moncef L. Nehdi

Sustainability 2023, 15(7), 5642; https://doi.org/10.3390/su15075642 - 23 Mar 2023

Cited by 7 | Viewed by 2349

Abstract

This research was conducted to forecast the uniaxial compressive strength (UCS) of rocks via the random forest, artificial neural network, Gaussian process regression, support vector machine, K-nearest neighbor, adaptive neuro-fuzzy inference system, simple regression, and multiple linear regression approaches. For this purpose, geo-mechanical [...] Read more.

This research was conducted to forecast the uniaxial compressive strength (UCS) of rocks via the random forest, artificial neural network, Gaussian process regression, support vector machine, K-nearest neighbor, adaptive neuro-fuzzy inference system, simple regression, and multiple linear regression approaches. For this purpose, geo-mechanical and petrographic characteristics of sedimentary rocks in southern Iran were measured. The effect of petrography on geo-mechanical characteristics was assessed. The carbonate and sandstone samples were classified as mudstone to grainstone and calc-litharenite, respectively. Due to the shallow depth of the studied mines and the low amount of quartz minerals in the samples, the rock bursting phenomenon does not occur in these mines. To develop UCS predictor models, porosity, point load index, water absorption, P-wave velocity, and density were considered as inputs. Using variance accounted for, mean absolute percentage error, root-mean-square-error, determination coefficient (R²), and performance index (PI), the efficiency of the methods was evaluated. Analysis of model criteria using multiple linear regression allowed for the development of a user-friendly equation, which proved to have adequate accuracy. All intelligent methods (with R² > 90%) had excellent accuracy for estimating UCS. The percentage difference of the average of all six intelligent methods with the measured value was equal to +0.28%. By comparing the methods, the accuracy of the support vector machine with radial basis function in predicting UCS was (R² = 0.99 and PI = 1.92) and outperformed all the other methods investigated. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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18 pages, 36833 KiB

Open AccessArticle

Finite Element Analysis for the Mechanism of Stress Wave Propagation and Crack Extension Due to Blasting of a Frozen Rock Mass

by Tingting Wang, Pingfeng Li, Chun’an Tang, Bingbing Zhang and Jiang Yu

Sustainability 2023, 15(5), 4616; https://doi.org/10.3390/su15054616 - 4 Mar 2023

Cited by 1 | Viewed by 1984

Abstract

The propagation mechanism of explosion stress waves in frozen rock mass is the main factor affecting the blasting efficiency and safety construction of strip mines in alpine cold regions. In order to study explosion stress wave propagation and crack extension in the blasting [...] Read more.

The propagation mechanism of explosion stress waves in frozen rock mass is the main factor affecting the blasting efficiency and safety construction of strip mines in alpine cold regions. In order to study explosion stress wave propagation and crack extension in the blasting process of frozen rock mass with ice-filled cracks, RFPA^2D is adopted to simulate the influence of the geometric parameters of ice-filled cracks (ice-filled crack thickness d, normal distance R from blasting hole to the ice-filled crack, and ice-filled crack angle α), loading intensity and loading rate on the explosion stress wave propagation effect and the damage range. The results show: The attenuation trend of explosion stress waves decreases gradually with an increase of thickness (e.g., In the case of R is 0.2 m, when d is 0.02 m, 0.04 m, and 0.08 m, the calculated attenuation factor of the minimum principal stress peak value is 7.128%, 18.056%, and 30.035%, respectively), and it decreases slightly with an increase of normal distance and ice-filled crack angle. The damage elements range of the ice-filled crack decreases when the ice-filled crack thickness and normal distance increases. The loading intensity and the loading rate have a significant influence on blasting hole fracture patterns. The ice-filled crack has a guiding effect on the growth of blasting cracks at the blasting hole. Nevertheless, the existence of ice-filled cracks inhibits the propagation of explosion stress waves in frozen rock mass. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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40 pages, 17924 KiB

Open AccessArticle

Analyzing Geotechnical Characteristics of Soils in Erbil via GIS and ANNs

by Zhvan Baqi Qader, Zuheir Karabash and Ali Firat Cabalar

Sustainability 2023, 15(5), 4030; https://doi.org/10.3390/su15054030 - 22 Feb 2023

Cited by 8 | Viewed by 3389

Abstract

The aim of this study is to analyze and model the geotechnical characteristics of soils in Erbil city using Geographic Information Systems (GIS) and Artificial Neural Networks (ANNs). The study used GIS to analyze the geotechnical properties of soils by collecting data from [...] Read more.

The aim of this study is to analyze and model the geotechnical characteristics of soils in Erbil city using Geographic Information Systems (GIS) and Artificial Neural Networks (ANNs). The study used GIS to analyze the geotechnical properties of soils by collecting data from 102 boreholes in three different depth levels (1.5 m–3.5 m, 3.5 m–6.5 m and 6.5 m–9.5 m) to visualize and analyze soil characteristics such as fines content, moisture content, soil plasticity, shear strength parameters, compressibility, Standard penetration test (SPT), and bearing capacity. The paper also establishes the prediction of SPT-N value and bearing capacity based on geotechnical properties of soils using ANN methods and made correlations between SPT values and shear strength parameters with the bearing capacity of the soil. The results analyzed via GIS indicated that the soil classification was silty clay with a small amount of sandy gravel (CL) in most of the study area. According to the SPT–N values, most of the soils in Erbil City ranged between 33 and 50; a higher SPT value generally indicates denser and stronger soil. The value of the shear strength parameter for the maximum friction angle of the soil layers was found to be 36°, and the predominant cohesion was approximately 100 kPa. The compression index of soils ranged between 0.11 to 0.31. The results showed that the ANN models were able to accurately predict the geotechnical parameters of the soil types in the study area. In addition, the use of GIS and ANN techniques allowed for a comprehensive analysis of the geotechnical characteristics of the soils in Erbil, providing valuable information for future construction and development projects. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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23 pages, 18804 KiB

Open AccessArticle

Experimental Study on Shear Strength Parameters of Round Gravel Soils in Plateau Alluvial-Lacustrine Deposits and Its Application

by Zhijun Kong, Yanhui Guo, Shilin Mao and Wei Zhang

Sustainability 2023, 15(5), 3954; https://doi.org/10.3390/su15053954 - 22 Feb 2023

Cited by 2 | Viewed by 2251

Abstract

The shear strength parameters of conglomerate soils are crucial to the stability analysis of foundation support when excavating and supporting ultra-deep foundation pits in the highland alluvial lacustrine layer. The difference in water content of conglomerate soils in different regions will directly affect [...] Read more.

The shear strength parameters of conglomerate soils are crucial to the stability analysis of foundation support when excavating and supporting ultra-deep foundation pits in the highland alluvial lacustrine layer. The difference in water content of conglomerate soils in different regions will directly affect the values of shear strength parameters. At the same time, more research on the shear strength of conglomerate soils under different water contents is required. In this study, a series of large-scale direct shear tests were carried out on the round gravel soil in the plateau alluvial-lacustrine deposit, and the round gravel soil’s shear strength curves under natural and saturated conditions and water content were obtained. The influence of different water content on the shear strength characteristics of the round gravel soil was discussed, and the shear strength parameters of the round gravel soil with different water content were used in the numerical simulation of ultra-deep foundation pit excavation and support. The stress and deformation laws of the foundation pit support were analyzed. The results show that the peak strength of the round gravel soil in the natural water content state appears between 30% and 45% of the shear displacement, while the peak strength in the saturated water content state appears around 45–55% of the shear displacement. The shear strength tends to be stable or slightly weakened with the increase of the shear displacement. The angle of internal friction and cohesion of round gravel soil in the natural water content state is greater than those in the saturated water content state. The simulation of the foundation excavation support shows that the shear strength parameter of the round gravel soil influences the force deformation of the support structure. The higher the water content of the round gravel soil, the more the shear strength parameter affects the soil displacement. The research results can provide some reference for optimizing project design parameters. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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20 pages, 4581 KiB

Open AccessArticle

Mining Method Optimization of Difficult-to-Mine Complicated Orebody Using Pythagorean Fuzzy Sets and TOPSIS Method

by Shuai Li, Qi Huang, Boyi Hu, Jilong Pan, Junyu Chen, Jianguo Yang, Xinghui Zhou, Xinmin Wang and Haoxuan Yu

Sustainability 2023, 15(4), 3692; https://doi.org/10.3390/su15043692 - 16 Feb 2023

Cited by 10 | Viewed by 1931

Abstract

In Suichang gold mine, the altered rock type gold deposits were cut by faults and joint fissures, leading to complex resource endowment characteristics, large changes in occurrence, a serious complex of ore vein branches and great difficulty in mining. In order to select [...] Read more.

In Suichang gold mine, the altered rock type gold deposits were cut by faults and joint fissures, leading to complex resource endowment characteristics, large changes in occurrence, a serious complex of ore vein branches and great difficulty in mining. In order to select a suitable mining method for such a difficult and complicated orebody, a multi-factor and multi-index comprehensive evaluation system involving benefits, costs, safety and other aspects was constructed by using the Pythagorean fuzzy sets and TOPSIS method. Taking Suichang gold mine as an example, the weighted aggregation evaluation matrix was constructed, the closeness index of the four mining schemes were 0.8436, 0.3370, 0.4296 and 0.4334, and the mechanized upward horizontal layering method was determined as the optimal scheme. This method overcame the fuzzy comparison of economic and technical indicators directly, but converted them into corresponding fuzzy numbers to obtain accurate closeness index for optimization. The application of this method not only ensured a safe, efficient and environment-friendly mining effect, but also provided a reference for the optimization of the mining scheme of the severely branched composite orebody. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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13 pages, 3064 KiB

Open AccessArticle

Study on Physical and Mechanical Properties of High-Water Material Made by Seawater

by Bangwen Lu, Changwu Liu, Jungang Guo and Naiqi Feng

Sustainability 2023, 15(4), 3334; https://doi.org/10.3390/su15043334 - 11 Feb 2023

Viewed by 1410

Abstract

In maritime engineering, marine-derived construction materials are seen as an efficient and cost-effective alternative. HWM is a novel inorganic cementitious material characterized by its high water content, rapid setting, and early strengthening. In this study, first, HWM was proposed to be produced from [...] Read more.

In maritime engineering, marine-derived construction materials are seen as an efficient and cost-effective alternative. HWM is a novel inorganic cementitious material characterized by its high water content, rapid setting, and early strengthening. In this study, first, HWM was proposed to be produced from seawater and used in a maritime environment. Two groups of HWM samples with varied w/c ratios were prepared with fresh water and seawater, and their behavior was examined to assess the viability of HWM produced with seawater. The microstructures and chemical compositions were studied using SEM and XRD. Results indicated that as the w/c ratio increased from 3:1 to 6:1, the water content, density, and uniaxial compressive strength of HWM produced from seawater varied from 72.1% to 77.5%; 1.25 to 1.12 g/cm³, and 1.47 MPa to 0.39 MPa, respectively, which is 2–10% lower, 0.8–2.2% higher, and 13–45% stronger than that from fresh water. The chemical composition of HWM mixed with seawater is predominantly composed of ettringite, C-S-H gel, aluminum (Al(OH)₃) glue, M-S-H gel, and Mg(OH)₂. SO₄²⁻ and Mg²⁺ in seawater participate in the hydration and hardening of HWM, resulting in an increase in the synthesis of ettringite and M-S-H gel, which makes the skeletal structure of HWM denser, hence increasing its strength. HWM derived from seawater retains excellent physical and mechanical properties. This work reveals the HWM-seawater interaction mechanism, elucidates the promising application prospect of HWM in maritime engineering, and paves the way to investigate its field performance. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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26 pages, 6655 KiB

Open AccessArticle

Estimating Flyrock Distance Induced Due to Mine Blasting by Extreme Learning Machine Coupled with an Equilibrium Optimizer

by Ramesh Murlidhar Bhatawdekar, Radhikesh Kumar, Mohanad Muayad Sabri Sabri, Bishwajit Roy, Edy Tonnizam Mohamad, Deepak Kumar and Sangki Kwon

Sustainability 2023, 15(4), 3265; https://doi.org/10.3390/su15043265 - 10 Feb 2023

Cited by 12 | Viewed by 2998

Abstract

Blasting is essential for breaking hard rock in opencast mines and tunneling projects. It creates an adverse impact on flyrock. Thus, it is essential to forecast flyrock to minimize the environmental effects. The objective of this study is to forecast/estimate the amount of [...] Read more.

Blasting is essential for breaking hard rock in opencast mines and tunneling projects. It creates an adverse impact on flyrock. Thus, it is essential to forecast flyrock to minimize the environmental effects. The objective of this study is to forecast/estimate the amount of flyrock produced during blasting by applying three creative composite intelligent models: equilibrium optimizer-coupled extreme learning machine (EO-ELM), particle swarm optimization-based extreme learning machine (PSO-ELM), and particle swarm optimization-artificial neural network (PSO-ANN). To obtain a successful conclusion, we considered 114 blasting data parameters consisting of eight inputs (hole diameter, burden, stemming length, rock density, charge-per-meter, powder factor (PF), blastability index (BI), and weathering index), and one output parameter (flyrock distance). We then compared the results of different models using seven different performance indices. Every predictive model accomplished the results comparable with the measured values of flyrock. To show the effectiveness of the developed EO-ELM, the result from each model run 10-times is compared. The average result shows that the EO-ELM model in testing (R2 = 0.97, RMSE = 32.14, MAE = 19.78, MAPE = 20.37, NSE = 0.93, VAF = 93.97, A20 = 0.57) achieved a better performance as compared to the PSO-ANN model (R2 = 0.87, RMSE = 64.44, MAE = 36.02, MAPE = 29.96, NSE = 0.72, VAF = 74.72, A20 = 0.33) and PSO-ELM model (R2 = 0.88, RMSE = 48.55, MAE = 26.97, MAPE = 26.71, NSE = 0.84, VAF = 84.84, A20 = 0.51). Further, a non-parametric test is performed to assess the performance of these three models developed. It shows that the EO-ELM performed better in the prediction of flyrock compared to PSO-ELM and PSO-ANN. We did sensitivity analysis by introducing a new parameter, WI. Input parameters, PF and BI, showed the highest sensitivity with 0.98 each. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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17 pages, 2816 KiB

Open AccessArticle

Stress and Deformation Characteristics of Tunnel Surrounding Rock under Alteration

by Yapeng Chen, Tong Wu, Xiaoshi Yan, Shang Shi, Jianyong Li and Jinyu Dong

Sustainability 2023, 15(2), 1161; https://doi.org/10.3390/su15021161 - 7 Jan 2023

Cited by 1 | Viewed by 2917

Abstract

Based on a typical project in an altered rock area, this study carried out numerical simulations using the FLAC^3D software to calculate the changes in the stress field, deformation field, and plastic zone of the surrounding rock during the unsupported and supported [...] Read more.

Based on a typical project in an altered rock area, this study carried out numerical simulations using the FLAC^3D software to calculate the changes in the stress field, deformation field, and plastic zone of the surrounding rock during the unsupported and supported excavation of a water transfer tunnel. The degree of alteration of the surrounding rock was considered as the base point. The following results were obtained: in the unsupported state, the tunnel surrounding rock was affected by different degrees of alteration, and compressive stress concentration appeared within a certain range at the bottom of the chamber. The value of all-directional stress decreased with the deepening of the degree of alteration, while the opposite was the case for the depth of influence. The displacement changes at the bottom and side walls of the chamber were large and increased significantly with the deepening of the degree of alteration; the displacement monitoring points distributed around the tunnel exhibited the same deformation trend. The plastic zone of the surrounding rock obviously expanded as the degree of alteration deepened. The stress, deformation field, and plastic zone of the tunnel surrounding rock were effectively controlled after the adoption of support measures. The results obtained by this study can be used as a reference for similar projects in altered rock areas. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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21 pages, 6702 KiB

Open AccessArticle

The Infrared Radiation Characteristics of Sandstone Fracture Seepage under Coupled Stress-Hydro Effect

by Ruoyu Cui, Kewang Cao, Xinci Li, Rana Muhammad Asad Khan, Naseer Muhammad Khan, Wei Liu, Qiangqiang Gao, Fagang Wang, Yuanzhong Yang, Jiangbo Quan and Saad S. Alarifi

Sustainability 2022, 14(24), 16454; https://doi.org/10.3390/su142416454 - 8 Dec 2022

Cited by 5 | Viewed by 1592

Abstract

Effective monitoring of rock fracture and seepage is an important information means to ensure the safety of geotechnical engineering. Therefore, sandstone samples were subject to uniaxial compression under different hydraulic conditions in the presence of infrared radiation and observation. This study uses the [...] Read more.

Effective monitoring of rock fracture and seepage is an important information means to ensure the safety of geotechnical engineering. Therefore, sandstone samples were subject to uniaxial compression under different hydraulic conditions in the presence of infrared radiation and observation. This study uses the multiple infrared radiation indexes (ΔAIRT, IRV, VDIIT) and image data to analyze the influence of coupled stress-hydro effect of infrared radiation change on sandstone surface. The main findings are: (1) The surface temperature of sandstone samples rises in the compaction and linear elastic stages, keeps stable or decreases in the fracture development stage, and rapidly decreases in the post-peak failure stage. (2) The samples with internal water pressure not more than 0.30 MPa, surface temperature and load curve at the compaction and linear elastic stage have a strong power function relationship, which a coefficient of determination is 0.8900. (3) The IRV curve appears as a pulse jump at the time of water seepage. After that, both the fracture development and the post-peak failure stages have stepped up. The VDIIT curve also appears to be a pulse jump at the time of water seepage, and obvious up and down fluctuations exist before water seepage and fracture. (4) Based on the Pauta Criterion, by analyzing the values of VDIIT during the experiment, the early warning threshold of sandstone fracture seepage is determined to be 0.00559. The research finding can provide an experimental and theoretical basis for the early warning of flood accidents in underground rock engineering. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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17 pages, 10256 KiB

Open AccessArticle

Advanced Analysis of Collision-Induced Blast Fragmentation in V-Type Firing Pattern

by Lalit Singh Chouhan, Avtar K. Raina, V. M. S. R. Murthy, Mohanad Muayad Sabri Sabri, Edy Tonnizam Mohamad and Ramesh Murlidhar Bhatawdekar

Sustainability 2022, 14(23), 15703; https://doi.org/10.3390/su142315703 - 25 Nov 2022

Cited by 2 | Viewed by 1854

Abstract

The firing pattern of blastholes influences the geometric aspects of a blast design in terms of change in blasting burden and spacing. This in turn changes the effective stiffness of a blasthole and confinement of the explosive and aids in better fragmentation. However, [...] Read more.

The firing pattern of blastholes influences the geometric aspects of a blast design in terms of change in blasting burden and spacing. This in turn changes the effective stiffness of a blasthole and confinement of the explosive and aids in better fragmentation. However, during the blasting, the fragments tend to collide and further fragment the rock. In comparison with other patterns, the V-type firing pattern increases the chances of collision between the fragments during flight. The process is scantly documented and accordingly field experiments were conducted using three firing patterns, viz., line, diagonal, and V-type, in a mine with minor variation in rock factor and minor to moderate changes in blast design variables. Sixteen blast design variables such as burden, spacing, charge per hole, in-hole charge density, etc. along with firing pattern were considered for the analysis and fragmentation modeled with the help of surface response analysis and artificial neural networks. The analysis revealed that there is a significant influence of firing patterns on fragmentation. The V-type pattern showed significant reduction in fragment sizes that can be ascribed to in-flight collision processes. A surface response model was developed using advanced ANOVA and resulted in an adjusted R² and RMSE of 0.89, 0.025, respectively. Further, modeling with ANN was attempted that showed better results than ANOVA with R² and RMSE of 0.96 and 0.040 in training, and 0.884 and 0.049 in validation tests. Since, diagonal and V-type patterns have similar design parameters, the reduction in fragment size in the former pattern can be ascribed to the collision of rock fragments during their flight in blasting. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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17 pages, 6009 KiB

Open AccessArticle

Spectrum Index for Estimating Ground Water Content Using Hyperspectral Information

by Kicheol Lee, Ki Sung Kim, Jeongjun Park and Gigwon Hong

Sustainability 2022, 14(21), 14318; https://doi.org/10.3390/su142114318 - 2 Nov 2022

Cited by 1 | Viewed by 1511

Abstract

Quality control considerably affects road stability and operability and is directly linked to the underlying ground compaction. The degree of compaction is largely determined by water content, which is typically measured at the actual construction site. However, conventional methods for measuring water content [...] Read more.

Quality control considerably affects road stability and operability and is directly linked to the underlying ground compaction. The degree of compaction is largely determined by water content, which is typically measured at the actual construction site. However, conventional methods for measuring water content do not capture entire construction sites efficiently. Therefore, this study aimed to apply remote sensing of hyperspectral information to efficiently measure the groundwater content of large areas. A water content prediction equation was developed through an indoor experiment. The experimental samples comprised 0–40% (10% increase) of fine contents added to standard sand. As high water content is not required in road construction, 0–15% (1% increase) of water content was added. The test results were normalized, the internal and external environments were controlled for precise results, and a wavelength–reflection curve was derived for each test case. Data variability analyses were performed, and the appropriate wavelength for water content reflection, as well as reflectance, was determined and converted into a spectrum index. Finally, various fitting models were applied to the corresponding spectrum index for water content prediction. Reliable results were obtained with the reflectance corresponding to a wavelength of 720 nm applied as the spectrum index. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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15 pages, 5400 KiB

Open AccessArticle

Assessment of the Blasting Efficiency of a Long and Large-Diameter Uncharged Hole Boring Method in Tunnel Blasting Using 3D Numerical Analysis

by Min-Seong Kim, Chang-Yong Kim, Myung-Kyu Song and Sean Seungwon Lee

Sustainability 2022, 14(20), 13347; https://doi.org/10.3390/su142013347 - 17 Oct 2022

Cited by 9 | Viewed by 2025

Abstract

Cut blasting is one of the most essential processes to reduce blast-induced vibration in tunnel blasting. The long and large-diameter uncharged hole boring (LLB) method is an example of one of the cut blasting methods, which utilizes large-diameter uncharged holes drilled in the [...] Read more.

Cut blasting is one of the most essential processes to reduce blast-induced vibration in tunnel blasting. The long and large-diameter uncharged hole boring (LLB) method is an example of one of the cut blasting methods, which utilizes large-diameter uncharged holes drilled in the tunnel face. In this study, blasting simulations were performed to analyze its blasting mechanism, and the LLB method and the traditional burn-cut method were simulated to compare their blasting efficiency. A 3D numerical analysis using LS-DYNA code, a highly non-linear transient dynamic finite element analysis using explicit time integration, was used to simulate the blasting process, and a Johnson–Holmquist constitutive material model, which is optimal for simulating brittle materials under dynamic conditions, was used to simulate the rock behavior under blasting. The modified LLB method showed a 3.75-fold increase in the advance per round compared to the burn-cut method, due to the increased formation of long and large-diameter uncharged holes compared to blast holes. This modified LLB method used 30% less explosives, so its failure range was approximately 1.25 times less than that of the burn-cut method, but its advance was approximately 4 times larger than the burn-cut method, which was similar to the original LLB method. This confirmed that the modified LLB method is significantly more efficient in terms of increased blasting efficiency (particularly the advance per round) as well as reduced blast-induced vibration, compared to the traditional cut blasting method. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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18 pages, 3153 KiB

Open AccessArticle

Estimation of Active Earth Pressure for Narrow Unsaturated Backfills Considering Soil Arching Effect and Interlayer Shear Stress

by Daxi Fu, Minghui Yang, Bo Deng and Hutao Gong

Sustainability 2022, 14(19), 12699; https://doi.org/10.3390/su141912699 - 6 Oct 2022

Cited by 1 | Viewed by 2165

Abstract

Affected by climatic conditions such as rainfall, evaporation and air temperature, most of the backfill soil is in an unsaturated state, and the decrease in matric suction leads to the failure of the retaining structure. In view of this, this study takes the [...] Read more.

Affected by climatic conditions such as rainfall, evaporation and air temperature, most of the backfill soil is in an unsaturated state, and the decrease in matric suction leads to the failure of the retaining structure. In view of this, this study takes the vertical rigid retaining wall with narrow unsaturated backfill as the research object, assuming that the backfill behind the wall forms a circular soil arch and considering the interlayer shear stress; thus, the analytical solution of the active earth pressure of narrow unsaturated soil is derived based on the thin layer element method. The reliability of this method is verified by comparing with the experimental and existing theoretical results. A parameter analysis demonstrates that with the increase in the interface friction angle of the moving wall–soil, the average shear stress coefficient of zone I and zone II increases gradually, but with the increase in the interface friction angle of the fixed wall–soil, the average shear stress coefficient of zone I decreases; with the increase in effective internal friction angle and effective cohesion, the active earth pressure decreases and the tension crack depth increases; with the increase in the interface friction angle, the active earth pressure in the upper part of the retaining wall increases slightly, while the active earth pressure in the lower part decreases obviously; with the increase in matric suction, the active earth pressure first decreases rapidly and then increases gradually, and the tension crack depth first increases and then decreases, but the distribution pattern of the horizontal active earth pressure remains unchanged; the active earth pressure decreases with the decrease in the aspect ratio, and when the aspect ratio is smaller, the attenuation is more obvious; until the aspect ratio reaches a certain value, the active earth pressure is basically unchanged. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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18 pages, 3916 KiB

Open AccessArticle

A New Discrete Form of Hoek–Brown Criterion and Its Application to Limit Equilibrium Analysis of Rock Slope Stability

by Youn-Kyou Lee and S. Pietruszczak

Sustainability 2022, 14(19), 12113; https://doi.org/10.3390/su141912113 - 25 Sep 2022

Cited by 2 | Viewed by 1558

Abstract

The generalized Hoek–Brown criterion (GHB) is recognized as one of the standard failure criteria in rock engineering and its validity extends to a wide range of rock mass quality. A drawback of this criterion is the difficulty of transforming it into an explicit [...] Read more.

The generalized Hoek–Brown criterion (GHB) is recognized as one of the standard failure criteria in rock engineering and its validity extends to a wide range of rock mass quality. A drawback of this criterion is the difficulty of transforming it into an explicit form defining the Mohr failure envelope when its strength parameter

a

is not equal to 0.5. The information on the functional form of the Mohr envelope for the full range of rock mass conditions enables the implementation of classical engineering approaches, such as the limit equilibrium method and limit analysis, in the framework of the GHB criterion. Knowing that for

a \neq 0.5

the exact closed-form representation of the Mohr envelope is not feasible, an alternative is to express it in an approximate analytical form. The main purpose of this study is to propose a new improved method to define an approximate Mohr envelope of the GHB criterion that is much more accurate compared with the recently published approximations. The idea behind the formulation is to expand the Balmer’s equation, which defines the relationship between the normal stress and minor principal stress at failure, by invoking the finite Taylor series centered at the known solution for

a = 0.5

. The formulation is then completed by substituting this solution into another Balmer’s equation, defining the relationship between the shear strength and the minor principal stress. The Taylor polynomial approximations of up to third degree are considered in the formulation. The accuracy of the shear strength prediction is shown to be much better than that of the approximate formula of Lee and Pietruszczak proposed in 2021. An illustrative example of limit equilibrium analysis of rock slope stability, incorporating the new approximate expression for the Mohr envelope, is provided. The analysis incorporates a modified version of the Bishop approach, which is simpler and more rigorous than the original nonlinear expression. The study confirms that the new approximate representation of the Mohr failure envelope can facilitate the application of the GHB criterion to a range of practical rock engineering calculations. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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15 pages, 3419 KiB

Open AccessArticle

Soil Liquefaction Prediction Based on Bayesian Optimization and Support Vector Machines

by Xuesong Zhang, Biao He, Mohanad Muayad Sabri Sabri, Mohammed Al-Bahrani and Dmitrii Vladimirovich Ulrikh

Sustainability 2022, 14(19), 11944; https://doi.org/10.3390/su141911944 - 22 Sep 2022

Cited by 6 | Viewed by 2203

Abstract

Liquefaction has been responsible for several earthquake-related hazards in the past. An earthquake may cause liquefaction in saturated granular soils, which might lead to massive consequences. The ability to accurately anticipate soil liquefaction potential is thus critical, particularly in the context of civil [...] Read more.

Liquefaction has been responsible for several earthquake-related hazards in the past. An earthquake may cause liquefaction in saturated granular soils, which might lead to massive consequences. The ability to accurately anticipate soil liquefaction potential is thus critical, particularly in the context of civil engineering project planning. Support vector machines (SVMs) and Bayesian optimization (BO), a well-known optimization method, were used in this work to accurately forecast soil liquefaction potential. Before the development of the BOSVM model, an evolutionary random forest (ERF) model was used for input selection. From among the nine candidate inputs, the ERF selected six, including water table, effective vertical stress, peak acceleration at the ground surface, measured CPT tip resistance, cyclic stress ratio (CSR), and mean grain size, as the most important ones to predict the soil liquefaction. After the BOSVM model was developed using the six selected inputs, the performance of this model was evaluated using renowned performance criteria, including accuracy (%), receiver operating characteristic (ROC) curve, and area under the ROC curve (AUC). In addition, the performance of this model was compared with a standard SVM model and other machine learning models. The results of the BOSVM model showed that this model outperformed other models. The BOSVM model achieved an accuracy of 96.4% and 95.8% and an AUC of 0.93 and 0.98 for the training and testing phases, respectively. Our research suggests that BOSVM is a viable alternative to conventional soil liquefaction prediction methods. In addition, the findings of this research show that the BO method is successful in training the SVM model. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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20 pages, 6359 KiB

Open AccessArticle

Mineral Texture Identification Using Local Binary Patterns Equipped with a Classification and Recognition Updating System (CARUS)

by Saeed Aligholi, Reza Khajavi, Manoj Khandelwal and Danial Jahed Armaghani

Sustainability 2022, 14(18), 11291; https://doi.org/10.3390/su141811291 - 8 Sep 2022

Cited by 4 | Viewed by 2043

Abstract

In this paper, a rotation-invariant local binary pattern operator equipped with a local contrast measure (riLBPc) is employed to characterize the type of mineral twinning by inspecting the texture properties of crystals. The proposed method uses photomicrographs of minerals and produces LBP histograms, [...] Read more.

In this paper, a rotation-invariant local binary pattern operator equipped with a local contrast measure (riLBPc) is employed to characterize the type of mineral twinning by inspecting the texture properties of crystals. The proposed method uses photomicrographs of minerals and produces LBP histograms, which might be compared with those included in a predefined database using the Kullback–Leibler divergence-based metric. The paper proposes a new LBP-based scheme for concurrent classification and recognition tasks, followed by a novel online updating routine to enhance the locally developed mineral LBP database. The discriminatory power of the proposed Classification and Recognition Updating System (CARUS) for texture identification scheme is verified for plagioclase, orthoclase, microcline, and quartz minerals with sensitivity (TPR) near 99.9%, 87%, 99.9%, and 96%, and accuracy (ACC) equal to about 99%, 97%, 99%, and 99%, respectively. According to the results, the introduced CARUS system is a promising approach that can be applied in a variety of different fields dealing with classification and feature recognition tasks. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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16 pages, 2618 KiB

Open AccessArticle

Investigation of Some Property Changes of Light-Colored Turkish Natural Stones after High-Temperature Treatments

by Engin Özdemir

Sustainability 2022, 14(16), 10298; https://doi.org/10.3390/su141610298 - 18 Aug 2022

Cited by 2 | Viewed by 1695

Abstract

Natural stones are a widely used construction material for both structural and decorative purposes. It is a material used for many floors and cladding due to its special beauty and quite aesthetic appearance. However, natural stones are exposed to different temperatures due to [...] Read more.

Natural stones are a widely used construction material for both structural and decorative purposes. It is a material used for many floors and cladding due to its special beauty and quite aesthetic appearance. However, natural stones are exposed to different temperatures due to natural, urban or industrial activities and they lose their physico-mechanical properties. It is known that high temperatures and fire cause degradation of construction and building stones. There are many studies investigating the effect of high temperatures on physical and mechanical properties of natural stones, while there are very limited studies on color and gloss. In this study, the changing physical and mechanical properties, color and gloss of different light-colored polished natural stones exposed to room temperature up to 1000 °C in the oven were investigated. For this purpose, natural stones were gradually exposed to 200, 400, 600, 800 and 1000 °C, starting from room temperature. After exposure to different temperatures, water absorption, porosity, Schmidt hammer hardness, point load strength, color and gloss were measured and compared to reference samples (at room temperature). However, all samples were decayed at 1000 °C, changes at this temperature value could not be determined. The results obtained at other temperature values were evaluated separately for each parameter. While the change in physico-mechanical properties of all samples up to 400 °C was limited, a dramatic change was observed with increasing temperature. In all samples, point load strength losses were observed due to an increase in porosity and water absorption. In addition, all samples darkened at 400 °C, while the whiteness value (L*) of samples increased at 800 °C. Gloss values gradually decreased due to the increase in temperature. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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19 pages, 17665 KiB

Open AccessArticle

The Evaluation of Rock Mass Characteristics against Seepage for Sustainable Infrastructure Development

by Muhammad Nasir Khurshid, Ammad Hassan Khan, Zia ur Rehman and Tahir Sultan Chaudhary

Sustainability 2022, 14(16), 10109; https://doi.org/10.3390/su141610109 - 15 Aug 2022

Cited by 2 | Viewed by 1913

Abstract

The determination of rock seepage characteristics is a complex phenomenon due to the variability, discontinuities, and formation age of rocks. The available literature on rock mechanics covers empirical relationships and approaches for the estimation of seepage characteristics from the rock mass parameters. In [...] Read more.

The determination of rock seepage characteristics is a complex phenomenon due to the variability, discontinuities, and formation age of rocks. The available literature on rock mechanics covers empirical relationships and approaches for the estimation of seepage characteristics from the rock mass parameters. In this study, an area comprising of infrastructure such as a water reservoir, embankments, roads, etc., constructed on mix rock mass formations was selected. The field and laboratory tests’ geo-mechanical data for the study area were evaluated. The data obtained from the field geo-mechanical engineering tests like Rock Quality Designation (RQD), Rock Core Recovery, Lugeon, etc., were analyzed. The data retrieved from the geological and geotechnical laboratory tests such as petrography, uniaxial compression, Hoek shear, elastic modulus, etc., were also evaluated. Rock mass was characterized based on petrographic and RQD, and was found in the hybrid formation of igneous, metamorphic, and sedimentary deposits. Seepage analysis in the study area was also carried out based on adit and piezometric data (installed in accordance with the mining technology guidelines), using Seep W Finite Element Method (FEM). The seepage observed in adits were compared with seepage calculated from Seep W. The trend of simulated flux was also presented against K ratio. Seepage quantities for different ranges of K ratio were plotted to evaluate interdependency between seepage and K ratio. Correlations of RQD were developed with hydraulic conductivity “k” for igneous, metamorphic, and sedimentary rocks for quick assessment of seepage characteristics of rock mass by RQD. These correlations and seepage related evaluations will be beneficial for the characterization of rock mass in relation to seepage for sustainable infrastructure development. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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27 pages, 7393 KiB

Open AccessArticle

Application of Machine Learning and Multivariate Statistics to Predict Uniaxial Compressive Strength and Static Young’s Modulus Using Physical Properties under Different Thermal Conditions

by Naseer Muhammad Khan, Kewang Cao, Qiupeng Yuan, Mohd Hazizan Bin Mohd Hashim, Hafeezur Rehman, Sajjad Hussain, Muhammad Zaka Emad, Barkat Ullah, Kausar Sultan Shah and Sajid Khan

Sustainability 2022, 14(16), 9901; https://doi.org/10.3390/su14169901 - 10 Aug 2022

Cited by 27 | Viewed by 2985

Abstract

Uniaxial compressive strength (UCS) and the static Young’s modulus (E_s) are fundamental parameters for the effective design of engineering structures in a rock mass environment. Determining these two parameters in the laboratory is time-consuming and costly, and the results may be [...] Read more.

Uniaxial compressive strength (UCS) and the static Young’s modulus (E_s) are fundamental parameters for the effective design of engineering structures in a rock mass environment. Determining these two parameters in the laboratory is time-consuming and costly, and the results may be inappropriate if the testing process is not properly executed. Therefore, most researchers prefer alternative methods to estimate these two parameters. This work evaluates the thermal effect on the physical, chemical, and mechanical properties of marble rock, and proposes a prediction model for UCS and E_S using multi-linear regression (MLR), artificial neural networks (ANNs), random forest (RF), and k-nearest neighbor. The temperature (T), P-wave velocity (P_V), porosity (η), density (ρ), and dynamic Young’s modulus (E_d) were taken as input variables for the development of predictive models based on MLR, ANN, RF, and KNN. Moreover, the performance of the developed models was evaluated using the coefficient of determination (R²) and mean square error (MSE). The thermal effect results unveiled that, with increasing temperature, the UCS, E_S, P_V, and density decrease while the porosity increases. Furthermore, ES and UCS prediction models have an R² of 0.81 and 0.90 for MLR, respectively, and 0.85 and 0.95 for ANNs, respectively, while KNN and RF have given the R² value of 0.94 and 0.97 for both E_S and UCS. It is observed from the statistical analysis that P-waves and temperature show a strong correlation under the thermal effect in the prediction model of UCS and E_S. Based on predictive performance, the RF model is proposed as the best model for predicting UCS and E_S under thermal conditions. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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16 pages, 35541 KiB

Open AccessArticle

Study on Damage Characteristics of Water-Bearing Coal Samples under Cyclic Loading–Unloading

by Hongxin Xie, Qiangling Yao, Liqiang Yu and Changhao Shan

Sustainability 2022, 14(14), 8457; https://doi.org/10.3390/su14148457 - 11 Jul 2022

Cited by 7 | Viewed by 1953

Abstract

For underground water reservoirs in coal mines, the complex water-rich environment and changing overburden stress can damage coal pillar dams. In this paper, the coal samples from coal seam 2² of Shangwan coal mine were taken as research objects and the damage [...] Read more.

For underground water reservoirs in coal mines, the complex water-rich environment and changing overburden stress can damage coal pillar dams. In this paper, the coal samples from coal seam 2² of Shangwan coal mine were taken as research objects and the damage mechanism and characteristics of coal samples with different moisture content and wetting-drying cycles under cyclic loading were investigated. The results show that as the moisture content and wetting-drying cycles increase, the post-peak stage of the coal samples under cyclic stress becomes obvious, and the hysteresis loop changes from dense to sparse. Compared to the uniaxial compression experiment, when w = 5.28% (the critical water content), mechanical parameters such as peak strength and modulus of elasticity decrease the most. Under cyclic loading, the damage mode of both sets of coal samples was tensile damage, but the increase in wetting-drying cycles promotes the development of shear fractures. For evaluating fracture types, the RA-AF density map is more applicable to wetting-drying cycle coal samples, whereas for the coal samples with different moisture contents this should be carried out with caution. This study can provide some theoretical basis for the stability evaluation of coal pillar dams in underground water reservoirs. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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12 pages, 5184 KiB

Open AccessArticle

A Safe and Efficient Mining Method with Reasonable Stress Release and Surface Ecological Protection

by Zhenghu Li, Junhui Zhang, Hui Chen, Xiuzhi Shi, Yanyang Zhang and Yanjun Zhang

Sustainability 2022, 14(9), 5348; https://doi.org/10.3390/su14095348 - 28 Apr 2022

Cited by 2 | Viewed by 1988

Abstract

Coal is an important basic energy source, widely distributed throughout the world, but resource abundance is uneven. Despite the need to develop and form new energy sources, coal energy maintains its dominant position. However, due to the uneven distribution and non-renewable nature of [...] Read more.

Coal is an important basic energy source, widely distributed throughout the world, but resource abundance is uneven. Despite the need to develop and form new energy sources, coal energy maintains its dominant position. However, due to the uneven distribution and non-renewable nature of coal resources, the relationship between the supply and demand of coal resources is tight. The rational exploitation of coal and reducing resource mining wastes are particularly important at the present stage. The original mining method of the Zhangjiamao coal mine resulted in a large waste of coal resources. After replacing the “110 construction method”, the original advanced end-support was canceled, which saved a lot of process time and engineering costs and greatly improved the mine production efficiency. With an average mining depth of +300 m, the working face is in a safe and stable state, and the 110-mining process has little impact on surface subsidence. Its successful application provides a reference experience for other mines to promote resource-saving and efficient mining. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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22 pages, 4185 KiB

Open AccessArticle

On the Physical and Mechanical Responses of Egyptian Granodiorite after High-Temperature Treatments

by Mohamed Elgharib Gomah, Guichen Li, Changlun Sun, Jiahui Xu, Sen Yang and Jinghua Li

Sustainability 2022, 14(8), 4632; https://doi.org/10.3390/su14084632 - 13 Apr 2022

Cited by 7 | Viewed by 1888

Abstract

In the design and stability of thermal engineering applications, a thorough understanding of the evolution of damage in the rock following high-temperature treatments is crucial. Hence, this study investigates the influence of high temperatures on Egyptian granodiorite rock properties, given its widespread use [...] Read more.

In the design and stability of thermal engineering applications, a thorough understanding of the evolution of damage in the rock following high-temperature treatments is crucial. Hence, this study investigates the influence of high temperatures on Egyptian granodiorite rock properties, given its widespread use as ornamental stones and aggregate material for roadways. Temperature effects up to 800 °C on its physical and mechanical responses were examined in conjunction with microstructure alterations. The results show that the density of granodiorite decreases after heat exposure due to a gain in volume and a loss in mass, with volume expansion being the most important component. In addition, the uniaxial compressive strength increases up to 400 °C before reducing linearly as the temperature increases, while the elastic modulus and P-wave velocity show a reducing trend with the temperature. This study suggests that granodiorite has a thermal damage threshold of 400 °C, beyond which its microstructure and physical and mechanical characteristics deteriorate, and granodiorite becomes less brittle and more ductile. Hence, at the mutation range (between 400 and 600 °C), the physical and mechanical responses shift from a stable to an unstable state. As a result, the microstructure of the granodiorite samples was destroyed at 800 °C, resulting in a significant drop in compressive strength and dilemmas in measuring the P-wave and elastic modulus. Accordingly, the findings of this study can be used to aid in the safe handling of this rock in high-temperature conditions. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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26 pages, 25553 KiB

Open AccessArticle

Accuracy of Two-Dimensional Limit Equilibrium Methods in Predicting Stability of Homogenous Road-Cut Slopes

by Fhatuwani Sengani and Dhiren Allopi

Sustainability 2022, 14(7), 3872; https://doi.org/10.3390/su14073872 - 25 Mar 2022

Cited by 9 | Viewed by 2811

Abstract

Although limit equilibrium methods are widely used by engineers and scientists in predicting the stability of homogenous slopes, their use has been demonstrated to present significant errors due to the violation of kinematic and static admissibility. The concern is often voiced regarding the [...] Read more.

Although limit equilibrium methods are widely used by engineers and scientists in predicting the stability of homogenous slopes, their use has been demonstrated to present significant errors due to the violation of kinematic and static admissibility. The concern is often voiced regarding the accuracy of limit equilibrium methods (LEMs) solutions in predicting the stability of homogenous slopes. There are no exact limit equilibrium solutions or charts available that could be used to check the LEMs solutions. The present study has used the rigorous upper and lower bounds solutions of limit analysis based on finite element formulations of the bound theorems to benchmark and develop an accuracy classification chart of limit equilibrium methods in predicting the stability of the homogenous slope. Six case studies of homogenous road-cut slopes that vary with material properties were used and the effect of the increase in material strength with depth was considered. The results of LEMs and limit analysis solutions have shown that Janbu simplified limit equilibrium solutions are closely related to those of rigorous upper bound solutions with an accuracy error ranging from 1 to 7% in various slope materials. Meanwhile, the Corp of Engineer 2 limit equilibrium solutions were found to overestimate among other methods, with an accuracy error ranging from 12 to 17% in various cases. Based on the results of the study an accuracy error classification chart of LEMs is developed. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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24 pages, 8746 KiB

Open AccessArticle

Machine Learning-Based Intelligent Prediction of Elastic Modulus of Rocks at Thar Coalfield

by Niaz Muhammad Shahani, Xigui Zheng, Xiaowei Guo and Xin Wei

Sustainability 2022, 14(6), 3689; https://doi.org/10.3390/su14063689 - 21 Mar 2022

Cited by 25 | Viewed by 3219

Abstract

Elastic modulus (E) is a key parameter in predicting the ability of a material to withstand pressure and plays a critical role in the design of rock engineering projects. E has broad applications in the stability of structures in mining, petroleum, geotechnical engineering, [...] Read more.

Elastic modulus (E) is a key parameter in predicting the ability of a material to withstand pressure and plays a critical role in the design of rock engineering projects. E has broad applications in the stability of structures in mining, petroleum, geotechnical engineering, etc. E can be determined directly by conducting laboratory tests, which are time consuming, and require high-quality core samples and costly modern instruments. Thus, devising an indirect estimation method of E has promising prospects. In this study, six novel machine learning (ML)-based intelligent regression models, namely, light gradient boosting machine (LightGBM), support vector machine (SVM), Catboost, gradient boosted tree regressor (GBRT), random forest (RF), and extreme gradient boosting (XGBoost), were developed to predict the impacts of four input parameters, namely, wet density (ρ_wet) in gm/cm³, moisture (%), dry density (ρ_d) in gm/cm³, and Brazilian tensile strength (BTS) in MPa on output E (GPa). The associated strengths of every input and output were systematically measured employing a series of fundamental statistical investigation tools to categorize the most dominant and important input parameters. The actual dataset of E was split as 70% for the training and 30% for the testing for each model. In order to enhance the performance of each developed model, an iterative 5-fold cross-validation method was used. Therefore, based on the results of the study, the XGBoost model outperformed the other developed models with a higher accuracy, coefficient of determination (R² = 0.999), mean absolute error (MAE = 0.0015), mean square error (MSE = 0.0008), root mean square error (RMSE = 0.0089), and a20-index = 0.996 of the test data. In addition, GBRT and RF have also shown high accuracy in predicting E with R² values of 0.988 and 0.989, respectively, but they can be used conditionally. Based on sensitivity analysis, all parameters were positively correlated, while BTS was the most influential parameter in predicting E. Using an ML-based intelligent approach, this study was able to provide alternative elucidations for predicting E with appropriate accuracy and run time at Thar coalfield, Pakistan. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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18 pages, 7597 KiB

Open AccessArticle

The Recent Progress China Has Made in High-Concentration Backfill

by Shuai Li, Zheng Yu, Haoxuan Yu and Xinmin Wang

Sustainability 2022, 14(5), 2758; https://doi.org/10.3390/su14052758 - 26 Feb 2022

Cited by 11 | Viewed by 2243

Abstract

With the development of science and technology, backfill technology has made continuous progress, and the traditional backfill method is no longer suitable for various complicated practical engineering situations. Therefore, researchers in the field of backfill mining have gradually shifted their research focus to [...] Read more.

With the development of science and technology, backfill technology has made continuous progress, and the traditional backfill method is no longer suitable for various complicated practical engineering situations. Therefore, researchers in the field of backfill mining have gradually shifted their research focus to the study of high-concentration backfill, and Chinese researchers are no exception. In order to solve the problems caused by the traditional backfill method, China began to vigorously develop high-concentration backfill in recent years, and achieved a lot of results. In this paper, some important achievements made by Chinese researchers on high-concentration backfill in recent years are reviewed; it also presents a summary report of the latest research results from several key laboratories across China. Therefore, this paper reviews the development progress of high-concentration backfill China has made, of which the main contents include: (1) research progress of the high-concentration backfill theory in China; and (2) research progress of high-concentration backfill equipment in China. Finally, we claim that this paper serves just as a guide to start a conversation, and we hope many more experts and scholars will be interested and engage in the research of this field. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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26 pages, 8249 KiB

Open AccessArticle

Hybrid Finite-Discrete Element Modelling of Various Rock Fracture Modes during Three Conventional Bending Tests

by Huaming An, Shunchuan Wu, Hongyuan Liu and Xuguang Wang

Sustainability 2022, 14(2), 592; https://doi.org/10.3390/su14020592 - 6 Jan 2022

Cited by 7 | Viewed by 2064

Abstract

The numerical techniques for modelling the rock fracture have been briefly reviewed. A hybrid finite-discrete element method (HFDEM) is proposed to simulate various fracture types of rock. A fracture model is implemented in the HFDEM for simulation of the three main fracture types. [...] Read more.

The numerical techniques for modelling the rock fracture have been briefly reviewed. A hybrid finite-discrete element method (HFDEM) is proposed to simulate various fracture types of rock. A fracture model is implemented in the HFDEM for simulation of the three main fracture types. In addition, the influence of the strain rate is considered during the HFDEM modelling rock behavior. Then, two typical rock mechanism tests are employed to calibrate the HFDEM. The proposed method has well modelled the rock fracture processes and can obtain reasonable stress distribution and force–displacement curves. After that, the HFDEM is used to model three convention bending tests. The obtained rock fracture processes indicates that the HFDEM can simulate various fracture types. The obtained rock strengths and fracture toughness indicate that the HFDEM can reflect the influence of the strain rate. It is concluded that the HFDEM can model the entire and complete rock fracture process during the three convention bending tests, and it also can capture the rock’s behavior on the strain rate. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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14 pages, 6399 KiB

Open AccessArticle

Experimental Test on Nonuniform Deformation in the Tilted Strata of a Deep Coal Mine

by Hai Wu, Qian Jia, Weijun Wang, Nong Zhang and Yiming Zhao

Sustainability 2021, 13(23), 13280; https://doi.org/10.3390/su132313280 - 30 Nov 2021

Cited by 42 | Viewed by 1901

Abstract

Taking a deep-mine horizontal roadway in inclined strata as our research object, the true triaxial simulation technique was used to establish a model of the inclined strata and carry out high-stress triaxial loading experiments. The experimental results show that the deformation of surrounding [...] Read more.

Taking a deep-mine horizontal roadway in inclined strata as our research object, the true triaxial simulation technique was used to establish a model of the inclined strata and carry out high-stress triaxial loading experiments. The experimental results show that the deformation of surrounding rock in the roadway presents heterogeneous deformation characteristics in time and space: the deformation of the surrounding rock at different positions of the roadway occurs at different times. In the process of deformation of the surrounding rock, deformation and failure occur at the floor of the roadway first, followed by the lower shoulder-angle of the roadway, and finally the rest of the roadway. The deformation amount in the various areas is different. The floor heave deformation of the roadway floor is the greatest and shows obvious left-right asymmetry. The deformation of the higher side is greater than that of the lower side. The model disassembly shows that the development of cracks in the surrounding rock is characterized by more cracks on the higher side and fewer cracks on the lower side but shows larger cracks across the width. The experimental results of high-stress deformation of the surrounding rock are helpful in the design of supports, the reinforcement scheme, and the parameter optimization of roadways in high-stress-inclined rock, and to improve the stability control of deep high-stress roadways. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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15 pages, 5107 KiB

Open AccessArticle

Optimized Support Vector Machines Combined with Evolutionary Random Forest for Prediction of Back-Break Caused by Blasting Operation

by Qun Yu, Masoud Monjezi, Ahmed Salih Mohammed, Hesam Dehghani, Danial Jahed Armaghani and Dmitrii Vladimirovich Ulrikh

Sustainability 2021, 13(22), 12797; https://doi.org/10.3390/su132212797 - 19 Nov 2021

Cited by 26 | Viewed by 2483

Abstract

Back-break is an adverse event in blasting works that causes the instability of mine walls, equipment collapsing, and reduction in effectiveness of drilling. Therefore, it boosts the total cost of mining operations. This investigation intends to develop optimized support vector machine models to [...] Read more.

Back-break is an adverse event in blasting works that causes the instability of mine walls, equipment collapsing, and reduction in effectiveness of drilling. Therefore, it boosts the total cost of mining operations. This investigation intends to develop optimized support vector machine models to forecast back-break caused by blasting. The Support Vector Machine (SVM) model was optimized using two advanced metaheuristic algorithms, including whale optimization algorithm (WOA) and moth–flame optimization (MFO). Before the models’ development, an evolutionary random forest (ERF) technique was used for input selection. This model selected five inputs out of 10 candidate inputs to be used to predict the back break. These two optimized SVM models were evaluated using various performance criteria. The performance of these two models was also compared with other hybridized SVM models. In addition, a sensitivity evaluation was made to find how the selected inputs influence the back-break magnitude. The outcomes of this study demonstrated that both the SVM–MFO and SVM–WOA improved the performance of the standard SVM. Additionally, the SVM–MFO showed a better performance than the SVM–WOA and other hybridized SVM models. The outcomes of this research recommend that the SVM–MFO can be considered as a powerful model to forecast the back-break induced by blasting. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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14 pages, 3634 KiB

Open AccessArticle

Mining Method Optimization of Gently Inclined and Soft Broken Complex Ore Body Based on AHP and TOPSIS: Taking Miao-Ling Gold Mine of China as an Example

by Qinqiang Guo, Haoxuan Yu, Zhenyu Dan and Shuai Li

Sustainability 2021, 13(22), 12503; https://doi.org/10.3390/su132212503 - 12 Nov 2021

Cited by 13 | Viewed by 2471

Abstract

The gently inclined thin to medium thickness ore body under a weak rock stratum is one of the typical difficult bodies to mine. In order to solve the fuzziness, randomness, and uncertainty in the process of mining method optimization for such ore bodies, [...] Read more.

The gently inclined thin to medium thickness ore body under a weak rock stratum is one of the typical difficult bodies to mine. In order to solve the fuzziness, randomness, and uncertainty in the process of mining method optimization for such ore bodies, a multi-level, multi-factor, multi-objective, and multi-index comprehensive evaluation system involving technology, economy, construction, and safety was constructed by combining the analytic hierarchy process (AHP) and technique for order preference by similarity to ideal solution (TOPSIS). Taking the Miao-ling gold mine in China as an example, the AHP-TOPSIS comprehensive decision model of mining method optimization is established, the comprehensive superiority degrees of the four mining schemes are 67.57%, 45.07%, 56.07%, and 31.63%, and the upward horizontal drift backfill mining method is determined as the optimal scheme. The method is verified in the actual production of the mine, which not only ensures the safe production of the mine, but also achieves better technical and economic effects. The research results provide a reference for the optimization of mining methods for gently inclined and soft broken complex ore bodies at home and abroad. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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18 pages, 3034 KiB

Open AccessArticle

Study on the Geological Condition Analysis and Grade Division of High Altitude and Cold Stope Slope

by Ruichong Zhang, Shiwei Wu, Chenyu Xie and Qingfa Chen

Sustainability 2021, 13(22), 12464; https://doi.org/10.3390/su132212464 - 11 Nov 2021

Cited by 3 | Viewed by 1709

Abstract

Analysis of the geological conditions of high-altitude and low-temperature stope slopes and the study of grade division are the basis for the evaluation of slope stability. Based on the engineering background of the eastern slope of the Preparatory iron mine in Hejing County, [...] Read more.

Analysis of the geological conditions of high-altitude and low-temperature stope slopes and the study of grade division are the basis for the evaluation of slope stability. Based on the engineering background of the eastern slope of the Preparatory iron mine in Hejing County, Xinjiang, we comprehensively analyse and summarize the factors that affect the geological conditions of high-altitude and cold slopes and finally determine nine geological conditions that affect the index parameters. Based on a back-propagation (BP) neural network algorithm, we establish an applicable network model to analyse the geological conditions of slopes in cold areas. The model is applied to the eastern slope to analyse and classify the geological conditions of the high-altitude and low-temperature slopes. The research results show that the skarn rock layer in the eastern slope is in a stable state and not prone to landslides, and its corresponding geological condition is Grade I; meanwhile, the monzonite porphyry rock layer is in a relatively stable state, with a potential for landslides and a corresponding geological condition Grade II. The marble rock layer is in a generally stable state, there is the possibility of landslide accidents, and the corresponding geological condition level is Grade III. The limestone rock layer is in an unstable state and prone to landslide accidents, it has a corresponding geology condition Grade IV. Therefore, the eastern slope can be divided into different geological condition regions: Zone I, Zone II, Zone III, and Zone IV, and the corresponding geological condition levels for these are Grade I, Grade II, Grade III, and Grade IV. These results may provide a basis for the stability evaluation of high altitudes and cold slopes. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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15 pages, 2904 KiB

Open AccessArticle

Nonlinear Elasto-Visco-Plastic Creep Behavior and New Creep Damage Model of Dolomitic Limestone Subjected to Cyclic Incremental Loading and Unloading

by Xingkai Wang, Leibo Song, Caichu Xia, Guansheng Han and Zheming Zhu

Sustainability 2021, 13(22), 12376; https://doi.org/10.3390/su132212376 - 9 Nov 2021

Cited by 12 | Viewed by 1918

Abstract

For many rock engineering projects, the stress of surrounding rocks is constantly increasing and decreasing during excavating progress and the long-term operation stage. Herein, the triaxial creep behavior of dolomitic limestone subjected to cyclic incremental loading and unloading was probed using an advanced [...] Read more.

For many rock engineering projects, the stress of surrounding rocks is constantly increasing and decreasing during excavating progress and the long-term operation stage. Herein, the triaxial creep behavior of dolomitic limestone subjected to cyclic incremental loading and unloading was probed using an advanced rock mechanics testing system (i.e., MTS815.04). Then, the instantaneous elastic strain, instantaneous plastic strain, visco-elastic strain, and visco-plastic strain components were separated from the total strain curve, and evolutions of these different types of strain with deviatoric stress increment were analyzed. Furthermore, a damage variable considering the proportion of irrecoverable plastic strain to the total strain was introduced, and a new nonlinear multi-element creep model was established by connecting the newly proposed damage viscous body in series with the Hookean substance, St. Venant body, and Kelvin element. The parameters of this new model were analyzed. The findings are listed as follows: (1) When the deviatoric stress is not more than 75% of the compressive strength, only instantaneous deformation, transient creep, and steady-state creep deformation occur, rock deformation is mainly characterized by the instantaneous strain, whereas the irrecoverable instantaneous plastic strain accounts for 38.02–60.27% of the total instantaneous strain; (2) Greater deviatoric stress corresponds to more obvious creep deformation. The visco-elastic strain increases linearly with the increase of deviatoric stress, especially the irrecoverable visco-plastic strain increases exponentially with deviatoric stress increment, and finally leads to accelerated creep and delayed failure of the sample; (3) Based on the experimental data, the proposed nonlinear creep model is verified to describe the full creep stage perfectly, particularly the tertiary creep stage. These results could deepen our understanding of the elasto-visco-plastic deformation behavior of dolomitic limestone and have theoretical and practical significance for the safe excavation and long-term stability of underground rock engineering. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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18 pages, 8684 KiB

Open AccessArticle

The Stability of Roadway Groups under Rheology Coupling Mining Disturbance

by Sen Yang, Guichen Li, Ruiyang Bi, Bicheng Yao, Ruiguang Feng and Yuantian Sun

Sustainability 2021, 13(21), 12300; https://doi.org/10.3390/su132112300 - 8 Nov 2021

Cited by 7 | Viewed by 1963

Abstract

The deep roadway groups play an important role in transportation and ventilation in coal mine production. Therefore, it is very important to comprehensively analyze the coupling effect of rheological deformation and coal mining on the stability of the roadway groups. In this paper, [...] Read more.

The deep roadway groups play an important role in transportation and ventilation in coal mine production. Therefore, it is very important to comprehensively analyze the coupling effect of rheological deformation and coal mining on the stability of the roadway groups. In this paper, the disturbance effects of different stop-mining lines on roadway groups under long-term rheology were investigated by numerical simulation, and the failure mechanism of roadway groups with large sections and multiple disturbances in a deep well was revealed. The results show that the long working face will lead to the collapse of key strata, and the influence range will spread to the adjacent roadway groups. When the distance between the working face and the stop-mining line is 100 m, the roadway groups cannot be affected by the working face mining, and the reserved width of the coal pillar can be determined to be 100 m, which increases the stability of the roadway’s surrounding rock and maintains the mine safety production. This paper aims to provide a reference for groups design and control under similar conditions. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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18 pages, 4310 KiB

Open AccessArticle

Experimental Study on Crack Propagation of Rock by Blasting under Bidirectional Equal Confining Pressure Load

by Jinjin Ge, Ying Xu, Wei Huang, Haibo Wang, Rongzhou Yang and Zhongyi Zhang

Sustainability 2021, 13(21), 12093; https://doi.org/10.3390/su132112093 - 2 Nov 2021

Cited by 14 | Viewed by 2203

Abstract

Rock blasting during tunneling has shown that the rock failure in high in situ stress environments is different from that in low in situ stress conditions or with a shallow rock mass. In particular, the propagation direction of the main crack induced by [...] Read more.

Rock blasting during tunneling has shown that the rock failure in high in situ stress environments is different from that in low in situ stress conditions or with a shallow rock mass. In particular, the propagation direction of the main crack induced by blasting is greatly affected by the in situ stresses. In order to study the law of crack propagation in rock during blasting under the conditions of an initial in situ stress, a transparent material that conformed to the mechanical properties of hard rock was used to carry out a similar model rock blasting test, under a unidirectional load. The results show that initial stress has a great influence on the propagation number, length, and direction of the main radial cracks. The specific performances were as follows: under the action of an equal confining pressure load, the longest main radial crack in the model specimen propagated along the diagonal direction, and the number and length of the main radial cracks propagated decreased with the gradual increase of confining pressure stress; in addition, the diameter of the circumferential cracks also decreased with the increase of stress, and there was a negative correlation between them. In view of the phenomenon where the longest main radial crack propagated along the diagonal direction in the model test, a mechanical model was established in this study to explain this process. This is of practical significance for understanding the mechanism of rock fracture when blasting with high in situ stresses. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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23 pages, 4514 KiB

Open AccessFeature PaperArticle

Factors Influencing Pile Friction Bearing Capacity: Proposing a Novel Procedure Based on Gradient Boosted Tree Technique

by Chia Yu Huat, Seyed Mohammad Hossein Moosavi, Ahmed Salih Mohammed, Danial Jahed Armaghani, Dmitrii Vladimirovich Ulrikh, Masoud Monjezi and Sai Hin Lai

Sustainability 2021, 13(21), 11862; https://doi.org/10.3390/su132111862 - 27 Oct 2021

Cited by 16 | Viewed by 3328

Abstract

In geotechnical engineering, there is a need to propose a practical, reliable and accurate way for the estimation of pile bearing capacity. A direct measure of this parameter is difficult and expensive to achieve on-site, and needs a series of machine settings. This [...] Read more.

In geotechnical engineering, there is a need to propose a practical, reliable and accurate way for the estimation of pile bearing capacity. A direct measure of this parameter is difficult and expensive to achieve on-site, and needs a series of machine settings. This study aims to introduce a process for selecting the most important parameters in the area of pile capacity and to propose several tree-based techniques for forecasting the pile bearing capacity, all of which are fully intelligent. In terms of the first objective, pile length, hammer drop height, pile diameter, hammer weight, and N values of the standard penetration test were selected as the most important factors for estimating pile capacity. These were then used as model inputs in different tree-based techniques, i.e., decision tree (DT), random forest (RF), and gradient boosted tree (GBT) in order to predict pile friction bearing capacity. This was implemented with the help of 130 High Strain Dynamic Load tests which were conducted in the Kepong area, Malaysia. The developed tree-based models were assessed using various statistical indices and the best performance with the lowest system error was obtained by the GBT technique. The coefficient of determination (R²) values of 0.901 and 0.816 for the train and test parts of the GBT model, respectively, showed the power and capability of this tree-based model in estimating pile friction bearing capacity. The GBT model and the input selection process proposed in this research can be introduced as a new, powerful, and practical methodology to predict pile capacity in real projects. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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14 pages, 3332 KiB

Open AccessArticle

Stability Analysis of Paste Filling Roof by Cut and Fill Mining

by Qingliang Chang, Yifeng Sun, Qiang Leng, Zexu Liu, Huaqiang Zhou and Yuantian Sun

Sustainability 2021, 13(19), 10899; https://doi.org/10.3390/su131910899 - 30 Sep 2021

Cited by 14 | Viewed by 2004

Abstract

Ensuring the stability of paste false rooves is an important issue in the study of the process of paste filling and slicing mining. Here, a mechanical model of a paste false roof is created to analyze its stability in the process of lower [...] Read more.

Ensuring the stability of paste false rooves is an important issue in the study of the process of paste filling and slicing mining. Here, a mechanical model of a paste false roof is created to analyze its stability in the process of lower slicing mining in order to determine the minimum slicing thickness of the false roof. We use FLAC3D to simulate and analyze the influence of changes in paste false roof thickness on the stability of the roof. The quantitative functional relationship between the thickness and the subsidence of a false roof, and the optimal thickness of the artificial paste roof, is finally obtained by the development law of the plastic zone in the lower slicing face. The results show that when the thickness of the paste false roof is 3.2 m, the roof can maintain its self-stabilization state and ensure the normal mining of lower layers. Because the same thickness of the upper and lower layers is beneficial for mining replacement and equipment selection in different layered working faces, the optimal thickness of a paste false roof is determined to be 3.2 m. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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21 pages, 5168 KiB

Open AccessArticle

The Effects of Rock Index Tests on Prediction of Tensile Strength of Granitic Samples: A Neuro-Fuzzy Intelligent System

by Yan Li, Fathin Nur Syakirah Hishamuddin, Ahmed Salih Mohammed, Danial Jahed Armaghani, Dmitrii Vladimirovich Ulrikh, Ali Dehghanbanadaki and Aydin Azizi

Sustainability 2021, 13(19), 10541; https://doi.org/10.3390/su131910541 - 23 Sep 2021

Cited by 32 | Viewed by 2403

Abstract

Rock tensile strength (TS) is an essential parameter for designing structures in rock-based projects such as tunnels, dams, and foundations. During the preliminary phase of geotechnical projects, rock TS can be determined through laboratory works, i.e., Brazilian tensile strength (BTS) test. However, this [...] Read more.

Rock tensile strength (TS) is an essential parameter for designing structures in rock-based projects such as tunnels, dams, and foundations. During the preliminary phase of geotechnical projects, rock TS can be determined through laboratory works, i.e., Brazilian tensile strength (BTS) test. However, this approach is often restricted by laborious and costly procedures. Hence, this study attempts to estimate the BTS values of rock by employing three non-destructive rock index tests. BTS predictive models were developed using 127 granitic rock samples. Since the simple regression analysis did not yield a meaningful result, the development of models that integrate multiple input parameters were considered to improve the prediction accuracy. The effects of non-destructive rock index tests were examined through the use of multiple linear regression (MLR) and adaptive neuro-fuzzy inference system (ANFIS) approaches. Different strategies and scenarios were implemented during modelling of MLR and ANFIS approaches, where the focus was to consider the most important parameters of these techniques. As a result, and according to background and behaviour of the ANFIS (or neuro-fuzzy) model, the predicted values obtained by this intelligent methodology are closer to the actual BTS compared to MLR which works based on linear statistical rules. For instance, in terms of system error and a-20 index, values of (0.84 and 1.20) and (0.96 and 0.80) were obtained for evaluation parts of ANFIS and MLR techniques, which revealed that the ANFIS model outperforms the MLR in forecasting BTS values. In addition, the same results were obtained through ranking systems by the authors. The neuro-fuzzy developed in this study is a strong technique in terms of prediction capacity and it can be used in the other rock-based projects for solving relevant problems. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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17 pages, 5299 KiB

Open AccessArticle

New Insights of Grouting in Coal Mass: From Small-Scale Experiments to Microstructures

by Yuantian Sun, Guichen Li, Junfei Zhang, Junbo Sun, Jiandong Huang and Reza Taherdangkoo

Sustainability 2021, 13(16), 9315; https://doi.org/10.3390/su13169315 - 19 Aug 2021

Cited by 25 | Viewed by 2239

Abstract

Pre-grouting as an effective means for improving the stability of roadways can reduce maintenance costs and maintain safety in complex mining conditions. In the Guobei coal mine in China, a cement pre-grouting technique was adopted to enhance the overall strength of soft coal [...] Read more.

Pre-grouting as an effective means for improving the stability of roadways can reduce maintenance costs and maintain safety in complex mining conditions. In the Guobei coal mine in China, a cement pre-grouting technique was adopted to enhance the overall strength of soft coal mass and provide sufficient support for the roadway. However, there are very limited studies about the effect of grouting on the overall strength of coal in the laboratory. In this paper, based on the field observation of a coal-grout structure after grouting, a series of direct shear tests were conducted on coal and grouted coal specimens to quantitatively evaluate the quality improvement of grouted coal mass. The results showed that the peak and residual shear strength, cohesion, friction angle and the shear stiffness of grouted coal were significantly improved with the increase of the diameter of grout column. Linear regression models were established for predicting these mechanical parameters. In addition, three failure models associated with coal and grouted coal specimens were revealed. According to microstructure and macroscopic failure performance of specimens, the application of the proposed models and some methods for further improving the stability of grouted coal mass were suggested. The research can provide the basic evaluation and guideline for the parametric design of cement pre-grouting applications in soft coal mass. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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26 pages, 77327 KiB

Open AccessArticle

Study on Evolution Mechanism of Structure-Type Rockburst: Insights from Discrete Element Modeling

by Chenxi Zhang, Diyuan Li, Shunchuan Wu, Long Chen and Jun Peng

Sustainability 2021, 13(14), 8036; https://doi.org/10.3390/su13148036 - 19 Jul 2021

Cited by 5 | Viewed by 2269

Abstract

Taking the “11.28” rockburst occurred in the Jinping II Hydropower Station as the engineering background, the evolution mechanism of structure-type rockburst was studied in detail based on the particle flow code. The results indicate that the failure mechanism of structure-type rockburst includes a [...] Read more.

Taking the “11.28” rockburst occurred in the Jinping II Hydropower Station as the engineering background, the evolution mechanism of structure-type rockburst was studied in detail based on the particle flow code. The results indicate that the failure mechanism of structure-type rockburst includes a tensile fracture induced by tangential compressive stress and a shear fracture caused by shear stress due to overburdened loadings and shear slip on the structural plane. In addition, it is found that the differences between structure-type rockburst and strainburst mainly include (a) the distribution of the local concentrated stress zone after excavation, (b) the evolution mechanism, and (c) the failure locations. Finally, the influence of four factors on the structure-type rockburst are explored. The results show that (1) when the friction coefficient is greater than 0.5, the effect of structural plane is weakened, and the rock near excavation tends to be intact, the structural-type rockburst intensity decreases; (2) the dissipated and radiated energy in structural-type rockburst reduces with rockmass heterogeneity m; (3) the lateral pressure coefficient has a significant effect on the intensity of deep rock failure, specifically in the form of the rapid growth in dissipative energy; (4) and the structural-type rockburst is more pronounced at a structural plane length near 90 mm. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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27 pages, 4659 KiB

Open AccessArticle

Statistical Assessment of the Effects of Grain-Structure Representation and Micro-Properties on the Behavior of Bonded Block Models for Brittle Rock Damage Prediction

by Carlos Efrain Contreras Inga, Gabriel Walton and Elizabeth Holley

Sustainability 2021, 13(14), 7889; https://doi.org/10.3390/su13147889 - 14 Jul 2021

Cited by 8 | Viewed by 3931

Abstract

The ability to predict the mechanical behavior of brittle rocks using bonded block models (BBM) depends on the accuracy of the geometrical representation of the grain-structure and the applied micro-properties. This paper evaluates the capabilities of BBMs for predictive purposes using an approach [...] Read more.

The ability to predict the mechanical behavior of brittle rocks using bonded block models (BBM) depends on the accuracy of the geometrical representation of the grain-structure and the applied micro-properties. This paper evaluates the capabilities of BBMs for predictive purposes using an approach that employs published micro-properties in combination with a Voronoi BBM that properly approximates the real rock grain-structure. The Wausau granite, with Unconfined Compressive Strength (UCS) of 226 MPa and average grain diameter of 2 mm, is used to evaluate the effectiveness of the predictive approach. Four published sets of micro-properties calibrated for granites with similar mineralogy to the Wausau granite are used for the assessment. The effect of grain-structure representation in Voronoi BBMs is analyzed, considering grain shape, grain size and mineral arrangement. A unique contribution of this work is the explicit consideration of the effect of stochastic grain-structure generation on the obtained results. The study results show that the macro-properties of a rock can be closely replicated using the proposed approach. When using this approach, the micro-properties have a greater impact on the realism of the predictions than the specific grain-structure representation. The grain shape and grain size representations have a minor effect on the predictions for cases that do not deviate substantially from the real average grain geometry. However, the stochastic effect introduced by the use of randomly-generated Voronoi grain-structures can be significant, and this effect should be considered in future studies. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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Review

Jump to: Research

15 pages, 6225 KiB

Open AccessReview

Bibliometric and Knowledge Network of Global Research on Pile Foundations: A Review of Recent Developments

by Aman Tiwari, Nitin Dindorkar and Suneet Kaur

Sustainability 2023, 15(14), 11108; https://doi.org/10.3390/su151411108 - 17 Jul 2023

Cited by 2 | Viewed by 1415

Abstract

Foundation on soft soil has always been a challenge for civil engineers and pile foundation is by far the most suitable and comprehensive idea for construction on soft soil. In this study, we produced a comprehensive overview of pile foundation research from 1992 [...] Read more.

Foundation on soft soil has always been a challenge for civil engineers and pile foundation is by far the most suitable and comprehensive idea for construction on soft soil. In this study, we produced a comprehensive overview of pile foundation research from 1992 to 2021 by making use of bibliometric analysis. This study was conducted based on the Web of Science Core Collection Database. In this analysis, data were retrieved and then sieved for different parameters to organize the data into various categories by means of Excel and VOS viewer. The objective of the research was to make an explanatory data set in order to help researchers in the pile foundation area. A database of 4803 publications has been retrieved. The analysis results show that the People’s Republic of China has yielded the greatest number of publications. Studies in this period are focusing on key factors associated with pile foundations such as soil structure interaction, pile group, settlement, liquefaction, bearing capacity etc. as suggested by the keywords analyzed in these publications. Analysis of the most cited articles in the field of Geotechnical and Geoenvironmental Engineering reveals that the research area has expanded from analyzing axial behavior and strength of pile foundations to analyzing seismic responses, further moving to sustainable structure and artificial intelligence applications in the concerned field in the last 30 years. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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20 pages, 6538 KiB

Open AccessReview

The State of the Art and New Insight into Combined Finite–Discrete Element Modelling of the Entire Rock Slope Failure Process

by Huaming An, Yuqing Fan, Hongyuan Liu, Yinyao Cheng and Yushan Song

Sustainability 2022, 14(9), 4896; https://doi.org/10.3390/su14094896 - 19 Apr 2022

Cited by 4 | Viewed by 2722

Abstract

The stability of rock slopes is of significance, as even the slightest slope failure can result in damage to infrastructure and catastrophes for human beings. Thus, this article focuses on the review of the current techniques available for rock slope stability analysis. The [...] Read more.

The stability of rock slopes is of significance, as even the slightest slope failure can result in damage to infrastructure and catastrophes for human beings. Thus, this article focuses on the review of the current techniques available for rock slope stability analysis. The rock slope stability techniques can be classified as conventional methods and numerical methods. The advantages and limitations of the conventional method are briefly reviewed. The numerical methods mainly included three types, i.e., continuum methods, discontinuum methods, and the combined/hybrid continuum–discontinuum methods. This article pays more attention to the last type. The combined/hybrid finite–discrete element method (FDEM), which might be the most widely used continuum–discontinuum method, is introduced and we illustrated its abilities in modelling the entire rock slope failure process. The fundamental principles of FDEM, i.e., the contact interaction of the discrete bodies and the transition from continuum to discontinuum, are introduced in detail. The abilities of the FDEM in modelling the rock slope failure process are calibrated by modelling the entire typical rock slope failure process. Then, the application of the FDEM in the analysis of slope stability is introduced and discussed. Finally, the authors give insight into the GPGUP-parallelized FDEM modelling of the high rock slope failure process by the implementation of the strength reduction method (SRM). It is concluded that the FDEM can effectively model the entire rock slope failure process, even without the implantation of any slope modes, and the GPGUP-parallelized FDEM is a promising tool in the study and application of rock slope stabilities. Full article

(This article belongs to the Special Issue Advances in Rock Mechanics and Geotechnical Engineering)

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