Water

Research

19 pages, 34334 KiB

Open AccessArticle

Hydrogeological Investigation of a Goaf and Subsidence Area Based on a Ground-to-Air Transient Electromagnetic Sounding Method

by Qicai Feng, Chang Li, Shuren Hao, Dongsheng Li, Tao Liu, Zhonglin Sun and Ling Zhou

Water 2024, 16(7), 1067; https://doi.org/10.3390/w16071067 - 7 Apr 2024

Viewed by 1218

Abstract

Water hazards in coal mines have always been the main geological hazard that restricts the safety of coal mine production. The traditional electromagnetic method is difficult to accurately detect the hydrogeological conditions of underground goafs due to accuracy and interference problems. The ground-to-air [...] Read more.

Water hazards in coal mines have always been the main geological hazard that restricts the safety of coal mine production. The traditional electromagnetic method is difficult to accurately detect the hydrogeological conditions of underground goafs due to accuracy and interference problems. The ground-to-air transient electromagnetic method is an electromagnetic detection technology with strong adaptability to various terrains, a large detection depth, a wide coverage, a high resolution, and fast speed. This paper mainly applies the ground-to-air transient electromagnetic method to conduct a hydrogeological engineering geological survey in a mine subsidence area. By using this method effectively, changes in hydrogeological and engineering geological conditions in the mine subsidence area are identified and water filling conditions below section 310 and section 250 of the roadway are determined. This study provides accurate and reliable basic data support for rescue operations and post-disaster reconstruction efforts, while also offering valuable insights for similar exploration projects. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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19 pages, 3518 KiB

Open AccessArticle

Study on the Influence of Water Erosion on the Bearing Capacity and Function of the High Pile Foundation of the Wharf

by Yashi Yang, Peng Zhang, Lingjun Wu and Qian Zhang

Water 2024, 16(4), 606; https://doi.org/10.3390/w16040606 - 18 Feb 2024

Viewed by 1279

Abstract

High-pile foundation is a common form of deep foundation commonly used in ocean environments, such as docks and bridge sites. Aiming at the problem of bearing capacity of high pile foundations, this paper proposes the calculation of bearing capacity and the analysis of [...] Read more.

High-pile foundation is a common form of deep foundation commonly used in ocean environments, such as docks and bridge sites. Aiming at the problem of bearing capacity of high pile foundations, this paper proposes the calculation of bearing capacity and the analysis of scour depth of high pile foundations under the action of scour based on the modified p-y curve. In this paper, three kinds of scour mechanisms—natural evolution scour, general scour, and local scour—are described; and the calculation methods of scour widely used at present are compared and analyzed. The solution of the vertical stress of soil around the pile under local scour is solved and applied to the β method to solve the lateral resistance of the pile under local scour. The local erosion is equivalent to the whole erosion, and the expression of the ultimate soil resistance before and after the equivalent is calculated, respectively, according to the principle that the ultimate soil resistance at a certain point above the equivalent pile end remains unchanged. The distance from the equivalent soil surface to the pile end can be obtained simultaneously, and then the equivalent erosion depth, p-y curve of sand at different depths, and high pile bearing capacity can be obtained. Finally, it is found that the bending moment of a single pile body varies along the pile body in the form of a parabola, and the maximum bending moment of the pile body is below the mud surface and increases with the increase in horizontal load. When the scouring depth is 30 m, the horizontal load is 25 KN, and the maximum bending moment of the pile body is about 150 N·m. The data with a relative error greater than 10% accounted for only 16.6% of the total data, and the error between the calculated value and the measured value was small. The formula can predict the erosion depth more accurately. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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16 pages, 20468 KiB

Open AccessArticle

Stability Assessment of Tunnels Excavated in Loess with the Presence of Groundwater—A Case Study

by Qihua Deng, Junru Zhang, Feng Lu, Ziyan Fan, Yi Wang and Zhi Lin

Water 2024, 16(4), 581; https://doi.org/10.3390/w16040581 - 16 Feb 2024

Cited by 1 | Viewed by 1073

Abstract

The high water content of the surrounding rock in loess tunnels will lead to the deterioration of rock strength, causing deformation and damage to the initial support structure and thereby affecting safety during construction and operation. This article first analyzes the strength characteristics [...] Read more.

The high water content of the surrounding rock in loess tunnels will lead to the deterioration of rock strength, causing deformation and damage to the initial support structure and thereby affecting safety during construction and operation. This article first analyzes the strength characteristics of loess under different water contents through indoor physical and mechanical tests. Secondly, based on numerical simulation results, the ecological environment, and design requirements, the water content threshold is determined. Finally, a reinforcement scheme combining surface precipitation measures and curtain grouting measures is proposed, and the reinforcement effect is analyzed based on on-site monitoring data. The results show that as the water content of loess increases, the cohesion, internal friction angle, and elastic modulus of the surrounding rock all decrease, leading to an increase in the sensitivity of the surrounding rock to excavation disturbances and a deterioration in strength. During the construction process, it shows an increase in the vault settlement and sidewalls’ convergence. During the process of increasing the distance between the monitoring section and the palm face, the settlement and convergence of the tunnel show a rapid growth stage, slow growth stage, and stable stage. The water content threshold is determined to be 22%. The reinforcement scheme of combining surface precipitation measures with curtain grouting measures not only meets the requirements of the ecological environment but also makes the settlement and convergence values lower than the yellow warning deformation values required by the design. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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21 pages, 9090 KiB

Open AccessArticle

Using Particle Swarm Optimization with Backpropagation Neural Networks and Analytic Hierarchy Process to Optimize the Power Generation Performance of Enhanced Geothermal System (EGS)

by Ling Zhou, Peng Yan, Yanjun Zhang, Honglei Lei, Shuren Hao, Yueqiang Ma and Shaoyou Sun

Water 2024, 16(3), 509; https://doi.org/10.3390/w16030509 - 5 Feb 2024

Cited by 2 | Viewed by 1270

Abstract

The optimization of the production scheme for enhanced geothermal systems (EGS) in geothermal fields is crucial for enhancing heat production efficiency and prolonging the lifespan of thermal reservoirs. In this study, the 4100–4300 m granite diorite stratum in the Zhacang geothermal field was [...] Read more.

The optimization of the production scheme for enhanced geothermal systems (EGS) in geothermal fields is crucial for enhancing heat production efficiency and prolonging the lifespan of thermal reservoirs. In this study, the 4100–4300 m granite diorite stratum in the Zhacang geothermal field was taken as the target stratum to establish a numerical model of water-heat coupling of three vertical wells. However, relying solely on numerical simulation for optimization is time-consuming and challenging for the determination of the globally optimal production plan. The present study proposes a comprehensive evaluation method for optimizing the performance of EGS power generation based on the integration of particle swarm optimization with backpropagation neural network (PSO-BPNN) and analytic hierarchy process (AHP). Five different PSO-BPNN models were constructed based on the numerical simulation data to predict different EGS power generation performance indexes, including the production temperature, the injection pressure, the total electricity generation, the electric energy efficiency and the levelized cost of electricity. Based on these PSO-BPNN models, the weights of various thermal development evaluation indexes were calculated by AHP to conduct a comprehensive evaluation of the power generation performance of the three vertical wells EGS. The results show that the PSO-BPNN model has good prediction accuracy for EGS prediction of various performance indicators, with a coefficient of determination (R²) exceeding 0.999. The AHP evaluation of all production schemes reveals that the optimal power generation scheme entails a well spacing of 580 m, water injection rate of 56 kg/s, injection temperature of 38 °C and fracture permeability of 2.0 × 10⁻¹⁰ m². Over a span of 30 years, this scheme can provide a total power generation capacity amounting to 1775 GWh, with an associated LCOE value of 0.03837 USD/kWh. This not only provides a reference for the development and optimization of geothermal systems in the Zhacang geothermal field but also provides a new idea for the optimization design of other geothermal projects. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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13 pages, 3030 KiB

Open AccessArticle

Simulation Study on the Mechanical Effect of CO₂ Geological Storage in Ordos Demonstration Area

by Chang Li, Shuren Hao, Shengjie Zhang, Yongqing Jiang and Zhidong Yi

Water 2024, 16(1), 144; https://doi.org/10.3390/w16010144 - 29 Dec 2023

Cited by 1 | Viewed by 1245

Abstract

In order to understand the long-term process of CO₂ storage and demonstrate its safety, multi-field coupled numerical simulation is considered a crucial technology in the field of geological CO₂ storage. This study establishes a site-specific homogeneous thermo-hydro-mechanical coupling model based on [...] Read more.

In order to understand the long-term process of CO₂ storage and demonstrate its safety, multi-field coupled numerical simulation is considered a crucial technology in the field of geological CO₂ storage. This study establishes a site-specific homogeneous thermo-hydro-mechanical coupling model based on TOUGH-FLAC3D coupling program using actual stratigraphic data from the Ordos demonstration area. The analysis investigates the transport behavior of CO₂ within the formation considering pore permeability homogeneity, incorporates redistribution of effective stress and rock deformation, and provides a mechanical evaluation of the effectiveness of CO₂ sequestration at this specific site. The findings indicate that: (1) the sealing effect of the cap rock depends on the difference of permeability between the reservoirs. The greater the permeability difference, the better the sealing effect. (2) High pore fluid pressure can lead to a decrease in the effective stress of rocks, causing deformation. After simulation calculations, the maximum deformation of rocks can reach 7.79 mm within a decade of CO₂ injection. (3) Under the condition of continuous CO₂ injection, the pore pressure will not be able to dissipate quickly and will continue to rise, and eventually shear failure will occur in the rock layer, but it is mainly concentrated in the lower part of the cap rock. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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20 pages, 7063 KiB

Open AccessArticle

Debris Flow Scale Prediction Based on Correlation Analysis and Improved Support Vector Machine

by Li Li, Zhongxu Zhang, Dongsheng Zhao, Yue Qiang, Bo Ni, Hengbin Wu, Shengchao Hu and Hanjie Lin

Water 2023, 15(23), 4161; https://doi.org/10.3390/w15234161 - 30 Nov 2023

Viewed by 1182

Abstract

The occurrence of debris flows are a significant threat to human lives and property. Estimating the debris flow scale is a crucial parameter for assessing disaster losses in such events. Currently, the commonly used method for estimating debris flow runoff relies on fitting [...] Read more.

The occurrence of debris flows are a significant threat to human lives and property. Estimating the debris flow scale is a crucial parameter for assessing disaster losses in such events. Currently, the commonly used method for estimating debris flow runoff relies on fitting techniques, which often yield low prediction accuracy and limited data representation capabilities. Addressing these challenges, this study proposes an improved grey wolf algorithm optimized support vector machine prediction model. The model’s effectiveness is validated using data from 72 debris flow events in Beichuan County. The results demonstrate a prediction accuracy of 95.9% using this approach, indicating its strong predictive capabilities for debris flow scale. Additionally, it is observed that the basin area, the basin relative, and the main channel length are the key factors influencing debris flow scale in Beichuan County. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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16 pages, 5707 KiB

Open AccessArticle

Experimental Study on the Stability of Shallow Landslides in Residual Soil

by Lin Yin, Chuansheng Huang, Shuren Hao, Li Miao, Junyi Li, Yonggang Qiu and Huo Liu

Water 2023, 15(21), 3732; https://doi.org/10.3390/w15213732 - 26 Oct 2023

Cited by 1 | Viewed by 1388

Abstract

Landslide disasters are one of the most severe geological hazards in China. Soil slopes are prone to triggering landslides under the influence of main factors such as rainfall, resulting in economic losses, casualties, and ecological damage. Taking a residual soil landslide in Xingguo [...] Read more.

Landslide disasters are one of the most severe geological hazards in China. Soil slopes are prone to triggering landslides under the influence of main factors such as rainfall, resulting in economic losses, casualties, and ecological damage. Taking a residual soil landslide in Xingguo County as an example, this study investigated the influencing factors and mechanical properties of soil slope stability under rainfall infiltration through physical model experiments. The main conclusions were as follows: with the increase in rainfall intensity, the amount of rainwater infiltration and the weight of the soil mass increased, which led to greater changes in soil pressure. The maximum amplitude of the experimental process was 5.51 kPa. The response time of pore water pressure under a rainfall intensity of 45 mm/h was 20–30 min earlier than that under a rainfall intensity of 21 mm/h, with a larger fluctuation range. The maximum amplitude of the experimental process was 6.66 kPa. Under the condition of rainfall intensity of 21 mm/h, the slope undergone local shallow sliding failure, while under the condition of rainfall intensity of 45 mm/h, the slope undergone overall shallow sliding failure. The physical model experimental results were consistent with the historical deformation of the landslide and the actual situation on site. The conclusions of the experiment can provide a reference for the research on the failure mechanism of similar landslides. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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25 pages, 17413 KiB

Open AccessArticle

Assessing the Susceptibility of Landslides in the Tuoding Section of the Upper Reaches of the Jinsha River, China, Using a Combination of Information Quantity Modeling and GIS

by Yunkai Ruan, Ranran Huo, Jinzi Chen, Weicheng Liu, Xin Zhou, Tanhua Wang, Mingzhi Hou and Wei Huang

Water 2023, 15(20), 3685; https://doi.org/10.3390/w15203685 - 21 Oct 2023

Cited by 1 | Viewed by 1388

Abstract

Combined with visible light remote sensing technology and InSAR technology, this study employed the fundamental principles of the frequency ratio model, information content model, and analytic hierarchy process to assess the susceptibility of the study area. Nine susceptibility assessment factors such as elevation, [...] Read more.

Combined with visible light remote sensing technology and InSAR technology, this study employed the fundamental principles of the frequency ratio model, information content model, and analytic hierarchy process to assess the susceptibility of the study area. Nine susceptibility assessment factors such as elevation, slope, aspect, water system, vegetation coverage, geological structure, stratum lithology, rainfall, and human activities were selected, and the factor correlation degree was calculated by using the relative area density value of the landslide. The frequency ratio model and information content model were selected to carry out landslide susceptibility zoning, and the accuracy of the two models was verified by the ROC curve and density method. The results indicate that the information content model performed relatively well. Therefore, the information model, combined with the analytic hierarchy process and fuzzy superposition method using the landslide point density map, was chosen to evaluate landslide susceptibility. The study area was divided into five levels of landslide hazard, ranging from low to high, using the natural discontinuity point method. The results show that the area of each hazard zoning is 197.48, 455.72, 408.21, 152.66, and 16.22 km² from low to high, and the proportion of landslides in the corresponding area is 0.17%, 1.60%, 3.88%, 8.41%, and 16.65%, respectively. It can be seen that with the increase in the hazard level, the proportion of landslides also increases significantly, which verifies the accuracy of the hazard results. Additionally, four representative landslides in the study area were selected for analysis to understand their characteristics and underlying mechanisms. The results revealed that these landslides were notably influenced by the density of the Jinsha River and the surrounding roads. The susceptibility assessment outcomes for geological disasters align well with the current situation of landslide occurrences in the Tuoding river section, demonstrating high accuracy. This study provides a scientific foundation for effective prevention and control measures against local landslide disasters. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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15 pages, 8092 KiB

Open AccessArticle

Stability Analysis of a Transmission Line Tower and Slope under Heavy Rainfall

by Zigui Wu, Chuansheng Huang, Shuren Hao, Junyi Li, Li Miao and Tongyuan Zhang

Water 2023, 15(20), 3654; https://doi.org/10.3390/w15203654 - 18 Oct 2023

Cited by 1 | Viewed by 1983

Abstract

In recent years, our country’s transmission lines have often been in danger due to geological disasters such as landslides when passing through fragile geological environments, which has brought great challenges and risks to the operation and maintenance of transmission lines. In order to [...] Read more.

In recent years, our country’s transmission lines have often been in danger due to geological disasters such as landslides when passing through fragile geological environments, which has brought great challenges and risks to the operation and maintenance of transmission lines. In order to understand the impact of transmission line towers on tower foundation slopes under heavy rainfall conditions, the influence of towers at different locations, rainfall intensities, and slopes on slope stability was analyzed by using Geo-Studio finite element analysis software. The results show that the slope has an important influence on the selection of the reasonable position of the tower. When the tower is located at the lower part of the slope, the safety factor of the slope is the highest. The safety factor of the slope is also reduced, and eventually the slope will be unstable and destroyed; the stability coefficient of the slope in the natural state is 1.221, which is in a stable state. Slopes are prone to overall sliding, with the spoil and overburden as the sliding body and the rock–soil contact surface as the sliding surface. This result provides a scientific basis for further understanding the influence mechanism of the slope angle at the location of the tower pole on this type of landslide under rainfall conditions. Further research can use the results of this paper as a benchmark to carry out corresponding experimental analysis and verification work. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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14 pages, 7898 KiB

Open AccessArticle

Hydrocarbon Potential and Reservoir Characteristics of Lacustrine Shale: A Case of Lower Jurassic in the Western Qaidam Basin, NW China

by Bingqiang Liu, Min Wang, Yupeng Cao and Zhiming Yan

Water 2023, 15(17), 3104; https://doi.org/10.3390/w15173104 - 30 Aug 2023

Viewed by 1031

Abstract

The Lower Jurassic lacustrine shale is well developed in the western Qaidam Basin and characterized by significant thickness and continuous distribution. Previous investigations have indicated its substantial potential as a shale gas resource. Based on experiments of organic carbon content, vitrinite reflectance, rock-eval [...] Read more.

The Lower Jurassic lacustrine shale is well developed in the western Qaidam Basin and characterized by significant thickness and continuous distribution. Previous investigations have indicated its substantial potential as a shale gas resource. Based on experiments of organic carbon content, vitrinite reflectance, rock-eval pyrolysis, X-ray diffraction, and low-temperature nitrogen adsorption, the hydrocarbon potential and reservoir characteristics of Lower Jurassic lacustrine shale in the western Qaidam Basin were systematically analyzed. The results show that the total organic carbon (TOC) content ranges from 1.71% to 4.49%, with an average of 2.98%. The kerogen belongs to type II–III. The vitrinite reflectance (R_o) ranges from 1.05% to 1.95%, with an average of 1.62%, indicating that the kerogen has reached the high thermal maturity stage (gas window). The maximum pyrolysis peak temperature (T_max) ranges from 408 °C to 580 °C, with an average of 498.38 °C, further supporting the high thermal maturity of the kerogen. The content of brittle minerals, including quartz, feldspar, pyrite, and carbonate, ranges from 21% to 44% (averaging 32.54%), which is comparable to shale minerals found in American Ohio shale. The pore structure of the shale is predominantly characterized by open parallel plate slit pores and inclined slit pores. The pore diameter distribution curve can be divided into two types, including unimodal distribution and bimodal distribution. Micropores and mesopores contribute significantly to the specific surface area, and mesopores account for the highest proportion of pore volume. The thermal evolution degree has a direct impact on pore development of shale reservoirs. The micropore, mesopore, macropore, and total pore volumes of lacustrine shale in the study area show a negative correlation with TOC content, indicating that the organic matter within the shale is probably still in the first pyrolysis stage. However, no significant correlation is observed between pore volume and clay mineral content or between pore volume and brittle mineral content due to the complex interplay of several geological factors. These findings contribute to a better understanding of the lacustrine shale gas resource potential and can guide future exploration and exploitation efforts. In addition, the systematic analysis of reservoir characteristics serves as a foundation for the introduction and exploration of new shale fracturing technologies, which is of great significance for reducing the consumption of water resources and mitigating potential geo-disasters. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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15 pages, 6673 KiB

Open AccessArticle

Comprehensive Analysis of the Failure Potential of a Motorway Landslide in Dabu County, China

by Sheng Chen, Yang Hao, Wencai Zhang, Ying Sun and Xue Liu

Water 2023, 15(14), 2675; https://doi.org/10.3390/w15142675 - 24 Jul 2023

Viewed by 1369

Abstract

Because the failure potential of a landslide is difficult to assess, a motorway landslide that has obviously deformed was used as a case study in this research. Several multi-integrated geotechniques, including field investigation, drilling, electrical resistivity tomography (ERT), stability analysis, and numerical simulations, [...] Read more.

Because the failure potential of a landslide is difficult to assess, a motorway landslide that has obviously deformed was used as a case study in this research. Several multi-integrated geotechniques, including field investigation, drilling, electrical resistivity tomography (ERT), stability analysis, and numerical simulations, were used to achieve this goal. Field investigation with drilling was used to roughly determine the failure potential mass boundary and the material composition ERT technique was further used to distinguish the structure and composition of underground materials; the results agreed well with the field investigation, as well as the drilling data in the lithology judgement. The above investigations also showed the failure potential mass is in a slow sliding state and the slip surface roughly follows the contact zone between the upper soil and bedrock. Next, stability analysis based on the limit equilibrium method (LEM) was used to judge the current stability status of the slope, and its factor of safety (FOS) was 1.2 under the natural condition, 1.05 under the earthquake condition, and 1.15 under the rainfall condition. Based on the assessed potential slip surface and digital elevation data, a three-dimensional smoothed particle hydrodynamics (SPH) model was used to simulate the failure potential process. The dynamic information of the run-out behavior, including velocity, movement distance, and frictional energy, can be obtained, which is useful for hazard prediction. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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13 pages, 4283 KiB

Open AccessArticle

Study on the Prevention and Control of Downhole Debris Flows Based on Disaster Chain Theory

by Xiangdong Niu, Kepeng Hou and Huafen Sun

Water 2023, 15(13), 2367; https://doi.org/10.3390/w15132367 - 27 Jun 2023

Cited by 7 | Viewed by 1525

Abstract

The occurrence of downhole debris flows in caving mines has burst, concealment, and destruction characteristics. This study aimed to investigate accurate prevention and control measures for downhole debris flows. The research background was a downhole debris flow in the Plan copper mine. The [...] Read more.

The occurrence of downhole debris flows in caving mines has burst, concealment, and destruction characteristics. This study aimed to investigate accurate prevention and control measures for downhole debris flows. The research background was a downhole debris flow in the Plan copper mine. The disaster chain theory was applied to study prevention and control methods for downhole debris flows. Using a model of source generation, chain breaking, and disaster reduction, we proposed accurate prevention and control measures for downhole debris flow disasters, which prevent and control the downhole debris flows at the source. The results showed that the disaster chain type of downhole debris flow disasters is the compound periodic cycle chain, which has the characteristics of the branch basin chain and the periodic cycle chain. Based on the chain-effect nature of disasters caused by downhole debris flows, active and passive prevention and control methods for downhole debris flow disasters were proposed. The active prevention and control measures for chain breaking and disaster reduction involve isolating the generation conditions from the source, inducing a downhole debris flow disaster. This prevention and control method is difficult to implement during the actual production process. The idea of disaster reduction through passive defensive chain breaking is based on the fact that if the three essential types of conditions for the downhole debris flow formation are not present at the same time, then a disaster accident of a downhole debris flow can be effectively prevented and controlled. Accordingly, the following measures are proposed for preventing and controlling downhole debris flows: (1) reinforcement measures applied to the slope body of the landslide material source in the collapse pit; (2) adopting comprehensive flood control measures such as locking, intercepting, dispersing, draining, and blocking under hydraulic conditions; (3) blocking the formation of the channel by adjusting the ore drawing conditions; (4) addressing the inducing factors by blasting with a small amount of explosive. According to the disaster chain theory, prevention, and control methods for downhole debris flow in caving mines were investigated in this study, which not only broadens the research of the debris flows but also fills the gap in the systematic research on downhole debris flows. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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17 pages, 5454 KiB

Open AccessArticle

Debris Flow Run-Out Prediction Based on the Shallow-Water Flow Numerical Model—A Case Study of Xulong Gully

by Yaowu Liu, Dongsheng Zhang, Decun Guo, Wantong He and Weiheng Zhang

Water 2023, 15(11), 2072; https://doi.org/10.3390/w15112072 - 30 May 2023

Cited by 1 | Viewed by 1816

Abstract

Here we present a method for predicting debris flow run-out based on a numerical model for shallow water flows, using a case study conducted on Xulong Gully, a proposed dam site for a hydropower station in the upper reaches of the Jinsha River. [...] Read more.

Here we present a method for predicting debris flow run-out based on a numerical model for shallow water flows, using a case study conducted on Xulong Gully, a proposed dam site for a hydropower station in the upper reaches of the Jinsha River. A field investigation and remote sensing interpretation methods were used to develop a comprehensive evaluation of debris flow zones and calculate the potential provenance volume in the Xulong Gully. Particle-size analysis was conducted on the early debris flow fan in the Xulong Gully to determine the rheological properties of the debris flow materials. A numerical model for shallow flows was constructed using the finite volume method to verify fluid motion across complex terrain and explore the debris flow run-out range with various provenance volumes. The model showed that for a total debris flow volume of less than two million m³, the debris flow impact area would remain within the Xulong Gully. However, if the total debris flow volume is more than two million m³, the debris flow would flush out into the Jinsha River, blocking a portion of the river. If all the provenance in the Xulong Gully were flushed out, the maximum flow velocity of the generated debris flow would be 11 m/s and the thickness of the debris flow at the Xulong Gully estuary would be about 28.8 m. The debris flow would completely block 470 m of the Jinsha River. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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19 pages, 20707 KiB

Open AccessArticle

Distribution Pattern and Influencing Factors for the Temperature Field of a Topographic Bias Tunnel in Seasonally Frozen Regions

by Wenbin Tang, Xiangdong Xu, Tao Zhang, Hong Wang and Jianxing Liao

Water 2023, 15(11), 2060; https://doi.org/10.3390/w15112060 - 29 May 2023

Cited by 2 | Viewed by 1492

Abstract

In seasonally frozen regions, highway tunnels are prone to shallow buried bias pressures near the inlet/outlet, which leads to highway tunnels not only bearing asymmetric loads, but also facing the threat of extreme weather. However, there is still no clear understanding of the [...] Read more.

In seasonally frozen regions, highway tunnels are prone to shallow buried bias pressures near the inlet/outlet, which leads to highway tunnels not only bearing asymmetric loads, but also facing the threat of extreme weather. However, there is still no clear understanding of the temperature field for topographically biased tunnel in seasonally frozen regions at present. Taking the Huitougou tunnel of Hegang-Dalian expressway as the object, this paper uses on-site monitoring, theoretical analysis, and numerical simulation to study the distribution law and influence factors of temperature field for topographically biased tunnel in seasonally frozen regions. The numerical results of the temperature field are in good agreement with the on-site monitoring data, which verified the accuracy of this numerical model based on the aerodynamic principle, turbulence model, and wall function method. Meanwhile, the effect of different slope angle and overburden thickness on the temperature field of the tunnel is further analyzed. It is found that when the slope angle increases, the temperature field in the tunnel surrounding rock changes accordingly. The connecting area between the surface and the tunnel temperature field is deflected from arch crown to the arch shoulder of the tunnel, resulting in a large change in the temperature of the shallow buried side, while minor change in the temperature of the deep buried side. The freezing depth of surrounding rock decreases with the rising slope angle. As the overburden thickness gradually increases, the temperature field of the surface surrounding rock and the tunnel surrounding rock gradually change from mutual influence to non-influence. When the overburden thickness exceeds 15 m, a “isolated temperature zone” appears in the middle with a temperature of 6~7 °C, the temperature field of the tunnel surrounding rock is basically not affected by the surface air temperature. These results can provide important theoretical and engineering guidance for the evaluation, construction, and maintenance of tunnel engineering in seasonally frozen regions. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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15 pages, 3790 KiB

Open AccessArticle

Spatiotemporal Variation in Saline Soil Properties in the Seasonal Frozen Area of Northeast China: A Case Study in Western Jilin Province

by Jiejie Shen, Yating Chen, Qing Wang and Huicheng Fu

Water 2023, 15(10), 1812; https://doi.org/10.3390/w15101812 - 10 May 2023

Cited by 4 | Viewed by 1734

Abstract

Due to the impact of climate change and human activities, the problem of soil salinization is increasingly prominent, posing a threat to the safety of the ecological environment and engineering construction. To understand the development tendency of soil salinization, this paper took the [...] Read more.

Due to the impact of climate change and human activities, the problem of soil salinization is increasingly prominent, posing a threat to the safety of the ecological environment and engineering construction. To understand the development tendency of soil salinization, this paper took the saline soil in Western Jilin province as the research object and carried out a long–term investigation into the basic properties of the soil at several monitoring stations. The results showed that the properties of saline soil in Western Jilin province changed regularly at the spatial and temporal scales. In the longitudinal profile, the water content, soluble salt content, and organic matter content in the soil vary greatly with the seasons at a depth range of 0–50 cm, while their changes below 50 cm are not significant. This is related to the influence depth of the external environment. Meanwhile, the content of sand is relatively stable in the depth direction, mostly between 5 and 15%, while the content of silt and clay fluctuates greatly, and there seems to be a mirror relationship between them. Along the N(W)–S(E) direction, the crystallization proportion of clay minerals gradually increases by about 28% because the relatively humid and hot climate is conducive to mineral crystallization. Over time, in the S(E) study area, the precipitation is relatively abundant, and the shallow soil is desalted due to leaching, resulting in high salt storage in the deep soil. However, in the N(W) study area, salt migrates upwards with water under the dominant effects of evaporation and freeze-thaw, leading to the accumulation of salt in shallow soil and a decrease in salt storage in deep soil. In addition, the saline soil in the study area has strong alkalinity, and the pH increases from 8.2 to 9.8 in the N(W)–S(E) direction. Overall, the soil salinization situation in Western Jilin is not optimistic. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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23 pages, 7996 KiB

Open AccessArticle

A Coupled Seepage–Deformation Model for Simulating the Effect of Fracture Seepage on Rock Slope Stability Using the Numerical Manifold Method

by Xiaolei Qu, Yunkai Zhang, Youran Chen, Youyang Chen, Chengzhi Qi, Elena Pasternak and Arcady Dyskin

Water 2023, 15(6), 1163; https://doi.org/10.3390/w15061163 - 17 Mar 2023

Cited by 4 | Viewed by 2181

Abstract

Modeling seepage problems in rock fractures is an interesting research approach to evaluating rock slope instability that is attracting increasing attention. In the present study, a coupled seepage–deformation model based on the numerical manifold method (NMM) is proposed, and the flow of groundwater [...] Read more.

Modeling seepage problems in rock fractures is an interesting research approach to evaluating rock slope instability that is attracting increasing attention. In the present study, a coupled seepage–deformation model based on the numerical manifold method (NMM) is proposed, and the flow of groundwater in a fracture network coupled with the effects of seepage pressure and rock deformation are discussed. A global equilibrium equation of the system and a local factor of safety (FoS) of arbitrary rock fractures are derived based on the principle of minimum energy, and a series of verification examples are calculated. The simulation results show the robustness and effectiveness of the proposed numerical model. Finally, a rock slope collapse accident caused by seepage effects is simulated by the proposed method, and the failure process of the slope is reproduced. The simulation results show that excessive hydraulic pressure caused the vertical fractures to open and augmented the rock mass deformation, eventually leading to the failure of the slope. The proposed method possesses the potential to simulate larger-scale engineering problems. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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25 pages, 14902 KiB

Open AccessArticle

Mechanism Study of Differential Permeability Evolution and Microscopic Pore Characteristics of Soft Clay under Saturated Seepage: A Case Study in Chongming East Shoal

by Meng Yao, Qing Wang, Qingbo Yu, Jianzhong Wu, Hui Li, Jiaqi Dong, Weitong Xia, Yan Han and Xinlei Huang

Water 2023, 15(5), 968; https://doi.org/10.3390/w15050968 - 2 Mar 2023

Cited by 3 | Viewed by 2147

Abstract

Artificial reclamation is one of the main means of land expansion in coastal cities. However, the permeability of underlying soft clay (USC), derived from the dredged load, has not been paid enough attention, although it is closely related to the long-term deformation and [...] Read more.

Artificial reclamation is one of the main means of land expansion in coastal cities. However, the permeability of underlying soft clay (USC), derived from the dredged load, has not been paid enough attention, although it is closely related to the long-term deformation and stability of foundation soil. Hence, this paper analyzes the relationship between permeability characteristics and microscopic pore characteristics of USC in Chongming East Shoal (CES), a typical multi-phase reclamation area, through a variable head permeability test, mercury intrusion porosimetry (MIP) test, and scanning electron microscope (SEM) test. Furthermore, grey relation entropy and Pearson correlation analysis are implemented to analyze the influence of micropore parameters on permeability. The results revealed that the seepage process of clay showed a transition from unstable seepage to relatively stable seepage. Meanwhile, the permeability coefficient (PC) attenuated with time cyclically, indicating the alternating effect of the closed and opened unstable seepage channels. During seepage, clay particles could be entrained by pore water and intercepted by pores, thus clogging seepage channels. Then, the increased pore water pressure could break through new seepage channels. The degree of pore clogging was positively correlated with the average cycle period of PCs, and this was also present in the relatively stable stage of PCs. A lower mesopores content, higher fractal dimension, and aggregated flocculate microstructure could promote the clogging effect and result in lower permeability efficiency. Affected by unstable seepage channels, soft clay may face long-term potential deformation in the future, which needs further investigation. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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22 pages, 15463 KiB

Open AccessFeature PaperArticle

Comparison of Machine Learning and Traditional Statistical Methods in Debris Flow Susceptibility Assessment: A Case Study of Changping District, Beijing

by Feifan Gu, Jianping Chen, Xiaohui Sun, Yongchao Li, Yiwei Zhang and Qing Wang

Water 2023, 15(4), 705; https://doi.org/10.3390/w15040705 - 10 Feb 2023

Cited by 7 | Viewed by 2367

Abstract

As a common geological hazard, debris flow is widely distributed around the world. Meanwhile, due to the influence of many factors such as geology, geomorphology and climate, the occurrence frequency and main inducing factors are different in different places. Therefore, the evaluation of [...] Read more.

As a common geological hazard, debris flow is widely distributed around the world. Meanwhile, due to the influence of many factors such as geology, geomorphology and climate, the occurrence frequency and main inducing factors are different in different places. Therefore, the evaluation of debris flow sensitivity can provide a very important theoretical basis for disaster prevention and control. In this research, 43 debris flow gullies in Changping District, Beijing were cataloged and studied through field surveys and the 3S technology (GIS (Geography Information Systems), GPS (Global Positioning Systems), RS (Remote Sensing)). Eleven factors, including elevation, slope, plane curvature, profile curvature, roundness, geomorphic information entropy, TWI, SPI, TCI, NDVI and rainfall, were selected to establish a comprehensive evaluation index system. The watershed unit is directly related to the development and activities of debris flow, which can fully reflect the geomorphic and geological environment of debris flow. Therefore, the watershed unit was selected as the basic mapping unit to establish four evaluation models, namely ACA–PCA–FR (Analytic Hierarchy Process–Principal Component Analysis–Frequency Ratio), FR (Frequency Ratio), SVM (Support Vector Machines) and LR (Logistic Regression). In other words, this research evaluates debris flow susceptibility by comparingit with two traditional weight methods (ACA–PCA–FR and FR) and two machine learning methods (SVM and LR). The results show that the SVM evaluation model is superior to the other three models, and thevalueofthe area under the receiver-operating characteristic curve (AUC) is 0.889 from the receiver operating characteristic curve (ROC). It verifies that the SVM model has strong adaptability to small sample data. The study was divided into five regions, which were very low, low, moderate, high and very high, accounting for 22.31%, 25.04%, 17.66%, 18.85% and 16.14% of the total study area, respectively, by SVM model. The results obtained in this researchagree with the actual survey results, and can provide theoretical help for disaster prevention and reduction projects. Full article

(This article belongs to the Special Issue Effects of Groundwater and Surface Water on the Natural Geo-Hazards)

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