Geotechnic and Geostructure Modelling for Landslides: Prediction and Control

1. Introduction

Landslides, as one of the most frequent and highly destructive geological disasters worldwide, pose a continuous and severe threat to human society [1]. With the intensification of climate change and the continuous expansion of human engineering activities, the frequency of landslides and their spatial extent have increased significantly on a global scale [2]. Effectively predicting and preventing this type of disaster has become a major challenge for the international geotechnical engineering community [3,4]. Due to its vast territory, complex geological conditions, diverse climate types, and the vigorous promotion of the Western Development Strategy and infrastructure construction, landslide prevention and control in China face particularly severe challenges [5]. Landslide patterns range from the deep canyons in the southwestern mountainous regions to the gully areas of the Loess Plateau [6,7,8], and from the typhoon- and rainstorm-prone zones along the southeastern coast to the freeze–thaw-sensitive areas in the northwestern part of China. Complex geological environments and extreme meteorological events interact synergistically, making slope instability a key bottleneck that restricts the safety and sustainable development of territorial space. Thus, a thorough investigation into the nurturing environment and triggering mechanisms of landslide disasters holds significant theoretical value and practical importance for establishing a disaster prevention and mitigation system suited to China’s national conditions.

Landslide disasters are often the result of the combined effects of multiple factors. Among these, external disturbances such as rainfall infiltration, seismic loading, freeze–thaw cycles, and rock weathering are key drivers of slope instability. These factors gradually undermine the slope’s stability by altering the physical and mechanical properties of the rock and soil mass, its stress state, and the seepage field distribution, eventually leading to disaster occurrence [9,10,11]. In view of this, three tasks are of critical importance: first, conducting in-depth research on the engineering properties of rock and soil masses; second, developing high-precision stability assessment methods; and third, constructing constitutive models that accurately reflect complex in-service conditions. These have become the core technical approaches for achieving “active prevention and control” of landslide disasters. Therefore, a profound understanding of the mechanisms of slope instability and the enhancement of engineering control capabilities fundamentally depends on the deep integration of advanced geotechnical engineering technologies, numerical simulation methods, monitoring and early warning systems, and landslide disaster prevention strategies.

Against this backdrop, this SI focuses on cutting-edge topics in landslide disaster research, presenting a series of recent research achievements centered on disaster causation mechanisms, advanced geotechnical engineering technologies, and refined modeling of geotechnical structures. The six included papers analyze slope instability mechanisms based on multi-field coupling theory and demonstrate innovative applications in novel physical experimental models, micro- and macro-mechanical property analyses, and high-performance numerical simulation methods. We anticipate that the exchange and discussion of these research findings will further advance the geotechnical engineering discipline, providing a solid scientific foundation and technical support for landslide disaster risk assessment, engineering design, and disaster prevention and mitigation, particularly in complex environments worldwide.

2. Main Contributions to the Special Issue

This Special Issue features six original research papers. Among them, three papers investigate the failure mechanisms of rock/soil slopes by integrating physical model experiments with numerical simulations and provide engineering recommendations. Two papers investigate the damage mechanisms of rock blocks, sediments, mudstone, and limestone under wet–dry cycles from both micro- and macro-scale perspectives. In addition, one paper analyzes the deformation characteristics of weak interlayers in slopes with varying water contents under temperature cycling using the THMC-B multi-field coupling simulation device.

These three papers integrate indoor experiments and numerical simulations to investigate three types of water-induced instability mechanisms in distinct engineering contexts. The first examines exposed oil pipelines in mountainous valleys, where flash flood-induced erosion poses significant risks [Contribution 1]. They find that larger pipe diameters accelerate soil failure and intensify erosion, whereas larger flow angles reduce downstream soil loss. During flash floods, flow field compression and vortex formation near the pipe invert significantly exacerbate erosion. Hence, these research findings provide valuable references for pipeline construction and soil conservation projects in mountainous regions. The second focuses on layered ion-adsorption-type rare earth ore slopes in southern China under the combined effects of rainfall and liquid infiltration [Contribution 2]. The results indicate that, in sandy–silty clay slopes, increased rainfall intensity promotes the formation of a saturated water-retention zone at the soil layer interface, leading to rapid pore-water pressure build-up and reduced shear strength. In silty–sandy clay slopes, the low permeability of the upper silty clay layer limits water infiltration, leading to interlayer water retention that softens the slope and increases the risk of instability. Moreover, they find that a higher initial moisture content prolongs infiltration, reduces matrix suction, and weakens shear strength. Under identical conditions, silty–sandy clay slopes exhibit higher safety factors than sandy–silty clay slopes, and the latter approach critical instability as rainfall intensity increases. The third analyzes lateral erosion in reinforced fine-grained tailings dams under overtopping conditions, focusing on the interactions among hydraulic scouring, particle migration, and geogrid reinforcement [Contribution 3]. The results demonstrate that reinforced specimens exhibit significantly reduced lateral erosion depths compared to unreinforced ones; smaller-aperture geogrids provide superior erosion resistance, whereas erosion depth increases with flow rate. Numerical simulations align well with experimental observations. These findings provide theoretical and engineering support for pipeline safety, slope stability, and green mine construction in complex hydrogeological environments [12].

The next two papers investigate the effects of wet–dry cycles on two distinct geotechnical systems: mudstone–limestone slopes in an open-pit mine and stabilized/solidified (S/S) sediments. Herein, for mudstone–limestone slopes in Southwest China, optimal sample preparation involves using a particle size of less than 1 mm and a drying temperature of 50 °C [Contribution 4]. As the number of cycles increases, the saturated density rises; water absorption and the permeability coefficient initially increase sharply, then stabilize, and finally decrease sharply. Compressive and shear strengths gradually decrease, while the internal friction angle remains nearly constant. Microscopic analysis reveals enlarged pores and variations in mineral content that weaken the material’s strength. Numerical simulations indicate that changes in the seepage field are most pronounced at the slope toe, where the transient saturated zone expands and the stability coefficient decreases. In addition, by the third cycle, local stability falls below overall stability, signaling a shift in landslide behavior. For S/S sediments [Contribution 5], increased wet–dry cycles reduce the unconfined compressive strength, with pore evolution being driven by the expansion of calcium silicate hydrate (CSH) skeleton pores (d > 10⁴ nm) and shrinkage of sediment aggregate pores (10² nm < d < 10⁴ nm). Pores smaller than 100 nm contribute 90% of the total pore area, and the expansion and shrinkage forces originate from particles smaller than 10 nm. Plastic deformation of both pore types jointly controls the material’s strength, gradually reducing the rate at which strength declines. Thus, these research findings reveal that wet–dry cycles alter pore structures and physical–mechanical properties across scales, providing a theoretical foundation for slope stability assessment and S/S additive optimization.

Another paper determines the influence of temperature cycling on weak interlayers in mine slopes using carbonaceous mudstone shale with varying moisture contents [Contribution 6]. They investigate 16 shear creep tests under temperature cycling (from −5 °C to 65 °C) using the THMC-B multi-field coupling simulation device. Furthermore, a rheological constitutive model is developed to characterize the damage evolution under varying moisture contents. The results show that increased moisture content rapidly reduces mechanical properties, making the material more prone to shear failure and shortening its overall creep duration. Higher moisture content also prolongs the deceleration phase of creep. Among them, the proposed model accurately captures the entire shear creep process, with fitting coefficients exceeding 0.95. Therefore, these findings provide valuable insights into the shear creep behavior of weak interlayers in mine slopes.

3. Conclusions

In this SI, we present six original studies that collectively advance our understanding of slope instability mechanisms under complex environmental conditions. Three papers investigate water-induced failures in three distinct engineering contexts: exposed oil pipelines subjected to flash floods, layered rare earth ore slopes subjected to rainfall infiltration, and reinforced tailings dams subjected to overtopping—highlighting the roles of pipe diameter, flow angle, interlayer water retention, and geogrid reinforcement in controlling erosion and slope/dam stability. Two papers examine the effects of wet–dry cycles on mudstone–limestone slopes and on S/S sediments, revealing multi-scale pore-structure evolution and its impact on mechanical degradation. Additionally, one paper determines the effects of temperature cycling on carbonaceous mudstone interlayers, demonstrating how increased moisture content accelerates both creep deformation and shear failure. Collectively, these findings provide theoretical and engineering insights for slope stability assessment, disaster prevention, and the sustainable design of geotechnical infrastructure.

The integrated utilization of physical model experiments, numerical simulations, and multi-scale characterization methods across these studies demonstrates the value of combining experimental and computational approaches to capture complex failure mechanisms. Herein, the findings contribute to improving design standards for pipelines, rare earth mining operations, tailings dam safety, and the long-term performance of stabilized materials under cyclic environmental loading. Furthermore, the multi-field coupled analysis and constitutive modeling presented herein provide robust tools for predicting instability under coupled thermal–hydraulic–mechanical–chemical (THMC) conditions. As extreme weather events intensify, the insights from this Special Issue support the development of resilient infrastructure and inform risk management strategies for geotechnical systems in mountainous and mining regions.