Editorial: Mechanical Properties and Engineering Applications of Special Soils

1. Introduction

Special soils refer to the soils with unique physical, mechanical, and engineering properties that are developed under specific geological environments and weathering conditions [1]. Generally, the characteristics of special soils, such as soft soil, loess, residual soil, expansive soil, frozen soil, moraines, and contaminated soil, present significant challenges in geotechnical design and construction on a global scale. In comparison to common sedimentary clay and sand, the mechanical properties of special soil exhibit significant differences, thereby introducing considerable complexities in engineering applications [2]. A comprehensive understanding of the characteristics of special soils is essential to ensuring safe and cost-effective engineering practices. Figure 1 provides typical examples of engineering geological disasters associated with different types of special soils [3,4,5,6,7,8]. It is evident that the soil properties pose a significant risk to the safety of engineering structures and construction. Based on a multitude of engineering case studies, engineering accidents associated with special soils differ from those in homogeneous soils primarily due to the inherent anisotropy and inhomogeneity. In particular, the mechanical properties of special soils play a crucial role in shaping the progression of geological disasters and engineering accidents.

To ensure the stability and safety of construction, special attention should be devoted to the adverse engineering characteristics of special soils. Moreover, appropriate engineering measures must be implemented for soil treatment and reinforcement. For engineering applications, it is essential to implement corresponding foundation treatment methods, such as replacement, compaction, grouting, and additional measures, in order to enhance the bearing capacity and stability of the foundation [9]. During the process of building design and construction, it is imperative to adequately consider the heterogeneity and take appropriate structural measures to mitigate the impact of heterogeneous settlement on the building [10]. Furthermore, as a result of advancements in materials science, an increasing number of novel materials are being utilized for the treatment and enhancement of special soils. For instance, nanomaterials and fiber-reinforced materials have demonstrated promising potential in enhancing soil’s strength and durability [11,12].

The Special Issue “Mechanical Properties and Engineering Applications of Special Soils” provided a significant opportunity for pioneering advancements, thereby fostering the progression of soil mechanics research into a new stage. Global collaboration among researchers is essential for exploring the intricacies of specialized soil and driving the progress of soil mechanics and sustainable development in engineering geology. Throughout this process, it is essential to not only focus on the leading trends in soil mechanics theory but also emphasize the translation of research findings into practical engineering applications to contribute technical guidance towards modern construction.

2. An Overview of the Published Articles

The first published paper, from Ter-Martirosyan et al. (contribution 1), aimed to investigate the effect of shear rate on the viscosity coefficient and strength characteristics of clayey soil. The findings held potential for enhancing the accuracy of settlement calculations for structures over time.

The study proposed by Yang et al. (contribution 2) examined the impact of rubber fibers on the shear strength and pore structure characteristics of expansive soil. The research findings, including optimal amounts of rubber fibers, soil porosity, and maximum strength, hold significant promise for applications of expansive soil.

From the third paper, Yan et al. (contribution 3) improved the shear strength of cemented soft clay by fiber reinforcement and revealed its mechanism. This study contributed to the advancement of high-performance soft soil, which is essential for ensuring the stability of slopes and foundations.

The study by Dafalla et al. (contribution 4) presents a novel approach for predicting the swelling properties of clay–sand mixtures. It offered insights into a method of predicting the expansion of clay–sand mixtures commonly used in liners.

Moreno-Maroto et al.’s research (contribution 5) focused on examining the overall structural stability of compacted bentonite. The findings from the experiment have important implications for future studies involving various materials and testing conditions such as compaction and moisture levels.

The sixth paper submitted by Zhu et al. (contribution 6) investigated the impact of different loading methods on the dynamic strain of saturated expansive soil. The findings hold significant implications for the design and construction of subway and underground structures in Hefei City.

The research carried out by Alcan et al. (contribution 7) sought to examine how various fiber reinforcements affect the load-bearing capacity of sand in the settlement of strip foundations. The results demonstrated that the reinforcement effectively redistributes stress generated by the special soil over a wider area.

Liu et al.’s study (contribution 8) discussed the mechanical properties of sliding and rolling friction systems and their application in vibration isolation frame structures. This study held great significance for the investigation of novel vibration isolation mechanisms.

The focus of Zhou et al.’s study (contribution 9) was the undisturbed soft soil in the Yangtze River floodplain. The findings served as valuable raw data for informing engineering construction requirements within the floodplain.

The paper submitted by Badarayani et al. (contribution 10) was focused on the one-dimensional loading/unloading behavior of sand–rubber mixtures. A new approach has been proposed for the reutilization of extensive amounts of discarded tires.

The primary focus of the study conducted by Xu et al. (contribution 11) was to investigate the Atterberg limit of diatomaceous soil. The findings contributed to a deeper understanding of the Atterberg limit of diatomaceous soil and offer insights for its classification.

Chen et al.’s research (contribution 12) examined the engineering practice and practical case of a karst site in Guilin with complex geological conditions, especially regarding groundwater. The findings offered references for the prevention and management of karst collapses.

Yilmazoglu and colleagues (contribution 13) focused on studying the maximum load-bearing capacity of shallow foundations on sandy soil. This paper represented a significant advancement in the characterization of the ultimate bearing capacity of shallow foundations situated on unsaturated sandy soil.

Wang et al. (contribution 14) discuss the nonlinear dynamic characteristics of loess after earthquakes. Results of the study were applied to the engineering design, which reduced the damage to soil structure caused by strong earthquakes.

Dong et al.’s work (contribution 15) was devoted to conducting macroscopic and microscopic evaluations of granite residual soil treated by cement. This study has provided valuable insights for the proper solidification and management of residual soil in geotechnical engineering practice.

The study by Zhang et al. (contribution 16) delved into the dynamic characteristics of calcareous sand treated with MICP technique. The findings of this investigation offered a quantitative analysis of the dynamic parameters of cemented sand.

The study conducted by Liu et al. (contribution 17) examined the contraction and expansion characteristics of weathered granite soil in southern China, as well as its influence on gully formation. The findings offered new perspectives on the process of gully erosion.

Wang et al.’s study (contribution 18) investigates the influence of temperature and zinc pollution concentration on the mechanical properties of red clay. These findings provided a solid foundation for the management of heavy metal-contaminated soil in Guilin, a city in southern China.

In the research conducted by Song et al. (contribution 19), the focus was on analyzing the shear strength and electrical resistivity of red clay using Zn²⁺ as the subject of investigation. The results of this study provided valuable insights into soil remediation approaches for sites contaminated with heavy metals.

The paper submitted by Song et al. (contribution 20) investigated the impact of lead ion contamination on the microstructural features of red clay. The research findings had significant implications for addressing heavy metal pollution in red clay.

Liu et al.’s study (contribution 21) offered a comprehensive overview of the research findings on the variations in swelling pressure of bentonite during thermochemical reactions, emphasizing discrepancies in swelling pressure values obtained through different testing methods.

The paper written by Zuluaga-Astudillo et al. (contribution 22) analyzed multiple sets of results regarding the physico-mechanical index of diatomaceous soil. The findings of this study highlight the complex geotechnical properties and significant potential of diatomaceous soil.

The 22 papers selected for publication in this Special Issue hve greatly advanced research on the mechanical properties of special soils and their engineering applications.

3. Conclusions

The mechanical properties of special soil are intricate and variable, exerting a significant influence on the stability and safety of engineering projects. Through in-depth investigation into its mechanical properties, implementation of effective engineering measures, and utilization of novel materials, the potential advantages of special soil in engineering applications can be completely realized, thereby enhancing engineering quality and safety. As science and technology continue to advance, there will be broader and deeper exploration into the mechanical properties and engineering applications of special soil. To further facilitate global scholarly exchange in this field, we are pleased to announce the upcoming release of a second issue dedicated to this topic.

We would like to extend our sincere appreciation to all the authors who have made significant contributions to this Special Issue, as well as to the editors of Applied Sciences for their diligent efforts in promoting this Special Issue.