Chang Zhou

Extreme climate events are fundamentally altering the hydrological cycle at regional and global scales, intensifying the frequency and magnitude of geological hazards driven by water–rock interactions

The Zigui Basin, located in the Three Gorges Reservoir Area, has developed numerous landslides due to its interlayering of sandstone and mudstone, geological structure, and reservoir operations. This study identifies a fourth type of landslide failure mode: an oblique-dip slope wedge (OdSW) landslide, based on the Wanshuitian landslide. Following four heavy rainfall events from 3 to 13 July 2024, this landslide exhibited significant deformation on the 17th and was completely destroyed within 40 min. The dimensions of the landslide were 350 m in length, 160 m in width, and 20 m in thickness, with a volume estimated at 8.0 × 10⁵ m³. The characteristics of landslide deformation and the changes in moisture content within the shallow slide body were ascertained using unmanned aerial vehicles, moisture meters, and mobile phone photography. The landslide was identified to have occurred within the weathered residual layer of mudstone, situated between two sandstone layers, with the eastern boundary defined by an inclined rock layer. Upon transitioning into the accelerated deformation stage, the landslide initially exhibited uniform overall sliding deformation, culminating in accelerated deformation destruction. The dip structure created terrain disparities, resulting in a step-like terrain on the left bank and gentler slopes on the right bank, with interbedded soil and rock in a shallow layer, because the interlayered soft and hard geological conditions caused varied weathering and erosion patterns on the riverbank slopes. The interbedded weak–hard stratum layer fostered the development of the oblique-dip slope wedge landslide. Based on the improved Green–Ampt model, we developed a stability prediction methodology for an oblique-dip slope wedge landslide and determined the rainfall infiltration depth threshold of the Wanshuitian landslide (9.8 m). This study aimed not merely to sharpen the evolution mechanism and stability prediction of the Wanshuitian landslide but also to formulate more effective landslide-monitoring strategies and emergency management measures.

Background: Rock engineering systems face escalating threats from extreme climatic events and the complexities of deep engineering, necessitating robust resilience to withstand multi-hazard disturbances. Traditional methods, based on static equilibrium analysis, prove unsuited to address the dynamic, nonlinear interactions inherent in these systems. Objective: This study proposes a resilience-oriented framework for rock engineering, emphasizing the system’s capacity to maintain or rapidly recover functionality following disturbances. The study proposes a conceptual model, evaluation method, and enhancement techniques to improve rock engineering resilience, based on the complex system science. Methods: A unified disaster resilience management system is proposed, synergizing multi-field monitoring, risk assessment, and rapid recovery strategies. Three resilience-enhancing techniques are presented, including grouting reinforcement, resilient anchor support, and high-pressure anchor injection-spraying collaborative control, optimize stress redistribution and fracture resistance in rock masses. Results: The framework redefines resilience as a quantifiable system property, enabling data-driven lifecycle management of geotechnical infrastructure. It provides actionable strategies to reconcile safety and sustainability in deep tunneling and slope stabilization projects. Conclusions: By redefining resilience as a quantifiable system property rather than a qualitative goal, the framework enables data-driven lifecycle management of geotechnical infrastructure.

In recent years, the increasing frequency of extreme weather events has exacerbated the severity of geological disasters. Therefore, it is important to understand the mechanisms of geological disasters under extreme rainfall conditions. From June to October 2021, Baoji City, Shanxi Province, China, experienced some extreme and continuous heavy rainfalls, which triggered more than 30 geological disasters. Those geo-disasters threatened the lives of 831 people and the safety of 195 houses. The field investigations found that most of these geological disasters were devastating collapses that occurred in the loess layer, primarily due to the cave dwelling construction. The shear strength, montmorillonite content, disintegration degree, and plasticity index of two typical loesses, namely the Sanmen Formation stiff clay and the Hipparion red clay, were analyzed, and their water sensitivities were evaluated. The failure mechanisms of the landslides, ground fissures, and collapses were analyzed and most of them were controlled by the cave dwelling construction and the strong water sensitivity of the loess. This study provides data for understanding shallow geological disasters induced by extreme rainfall in the loess area, which are more threatening than large geological disasters. We proposed an intensity–duration (I–D) rainfall threshold as I = 90 D^−0.92, which relates the rainfall intensity (I) to the rainfall event duration (D). The empirical threshold provides some useful information for the early warning of collapses or landslides in similar geological settings in the loess area.

The movement process of debris flow in the complex roads system is important for risk evaluation and emergency rescue. This paper presents an in-depth study of the diversion effect of debris flow in cross channels, a common branching structure in both natural and engineered environments, especially in the field of urban debris flow prevention. A mathematical model is established based on the conservation of mass, momentum, and energy, and a solid–liquid two-phase motion equation for debris flow is derived from two-phase flow theory. A numerical solution method, combining the finite difference method and finite volume method, is employed to discretize and solve the equation. The model’s validity and effectiveness are confirmed through a numerical simulation of a typical engineering case and comparison with existing experimental data or theoretical results. This study reveals that debris flow at cross channels exhibits a diversion phenomenon, with some debris flow continuing downstream along the main channel and some diverting into the branch channel. The diversion rate, defined as the ratio of outlet flow to inlet flow of the branch channel, indicates the magnitude of this effect. This research shows that the solid–liquid ratio, inflow, width ratio, height ratio, and angle of the cross channel significantly impact the diversion effect. A series of numerical simulations are conducted by altering these parameters as well as the physical properties of debris flow and boundary conditions. These simulations analyze changes in flow rate, velocity, pressure, and other parameters of debris flow at cross channels, providing insights into the factors and mechanisms influencing the diversion effect. This research offers a robust instrument for comprehending and forecasting the dynamics of urban debris flows. It contributes significantly to mitigating the effects of debris flows on city infrastructure and enhancing the safety of city dwellers.

The understanding of the mechanical properties of sensitive marine clay subgrade stabilized with cement is vital for the safe, economical, and durable design of road structures. As the curing temperature affects the cement hydration progress, it is necessary to investigate the influence of the temperature on the evolution of the mechanical properties of cement-reinforced marine clay in road construction. A column testing and relevant monitoring program were performed to study the effect of various curing temperatures (2 °C, 22 °C, and 40 °C) on the mechanical properties’ development of cement-reinforced clay within 28 days. After these cement clay samples were cured for a specific time (1, 3, 7, and 28 days), they were subjected to two mechanical tests (i.e., California Bearing Ratio (CBR) test and uniaxial compressive strength (UCS) test). The findings reveal that a higher curing temperature accelerates cement hydration and self-desiccation. Consequently, the UCS and CBR values increase with curing temperature and the strength might vary by more times, especially for early age (≤7 days) samples. The results of this study contribute to a deeper understanding of the influence of temperature on the mechanical properties of the cement-reinforced clay and thus provide practical guidance with regards to road construction in the field.

At 10:05 a.m. on 4 February 2022, the perilous rock mass Yizhuxiang in Leizu Town, Yuan’an County, Hubei Province, China collapsed on a large scale. The Yizhuxiang collapse was about 35 m in length, 52 m in height, and 29 m in maximum thickness. The volume of the collapse was 5.32 × 104 m³. It threatened the transport of the national trunk road, destroyed the branch road and some cement mixing station workshops, and caused serious economic losses. The rock mass exposed in the collapse was dolomite with developed joint fractures. Under the effects of mining and unloading, fractures occurred in the rock mass; the top of the rock mass was bent and deformed towards the free face; and tension cracks were formed on the rear edge. The safety ore pillar directly below the collapsed body was compressed and deformed under the action of gravity, thus accelerating the internal deformation of the rock mass and leading to the formation of multiple dominant joints inside the rock mass. In the winter of 2021, the weather was extreme, with heavy snowfall and low temperatures. Under the effects of freeze–thaw, the strength of the rock mass declined and the tension cracks further expanded so that the rock mass experienced an accelerated deformation and finally collapsed. Causes of the collapse include mining activity beneath the collapsed mass and heightened extreme weather. The cause of the landslide disaster in this area is, however, freeze–thaw, which deserves the attention of scholars and the vigilance of the local government.