The frequent occurrence of extreme rainfall events often triggers levee slope failure (LSF), which, due to the levee effect, significantly damages the roads behind the levee. This paper presents a novel framework for the quantitative risk assessment of roads posed by LSF. Within the framework, the innovative integration of Monte Carlo simulation (MCS) and Material point method (MPM) provides a unique solution for simulating the complicated dynamic relationship between LSF and road destruction. MCS generates precise failure scenarios for MPM simulations, overcoming the limitations of traditional approaches in addressing uncertainty in complex scenario systems. With its technical superiority in capturing post-failure deformations, MPM offers critical insights for assessing road exposure and vulnerability. The framework also accounts for indirect losses from road disruptions, which have long been overlooked. The application of the framework to the risk assessment of the road behind the Shijiao Levee in the Pearl River Basin fully demonstrates its practicality and robustness. Compared to traditional risk assessment methods, the proposed framework provides a more refined dynamic evaluation, facilitating the formulation of more effective disaster mitigation strategies.

Granite saprolite (GS) slope failure is a common yet catastrophic phenomenon in South China. Although the impact of subtropical climate, characterized by high temperatures and heavy rainfall, is widely recognized, the effect of the capillary imbibition and drying (CID) process, which frequently occurs during the dry season, on the hydro-mechanical properties of GS and slope stability is largely overlooked. This research examines natural GS specimens with various degrees of weathering subjected to CID cycles. The study investigates the capillary imbibition (CI) process and the evolution of the soil's hydromechanical properties across CID cycles. The results indicate that the CI process in GS is fundamentally different from that in clays and sands. The aggregated structure of GS comprising numerous fissures and large pores plays a critical role. In addition, the CID cycles cause the hydro-mechanical degradation of GS, including a finer particle composition, decreased shear strength, and increased permeability and disintegration potential, where damage to soil cementation and fissure development are identified as critical factors. This investigation reveals new insights into the mechanical properties of GS that are essential for the development of effective landslide management strategies in South China. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Slope failure, as a natural disaster, can cause extensive human suffering and financial losses worldwide. This paper introduces a new soil moisture extended cohesive damage element (SMECDE) method to predict railway slope failure under heavy rainfall. A correlation between rainfall intensity and soil moisture content is first established to create an equivalence between the two. Considering slope failure mechanisms dominated by the loss of soil or the cohesion of slope materials due to heavy rainfall infiltration, the soil moisture decohesion model (SMDM) is developed using previous experimental data to express how soil cohesion varies with different soil moistures and depths. The SMDM is incorporated into the extended cohesive damage element (ECDE) method to fundamentally study slope failure mechanisms under varying soil moisture levels and depths. The proposed SMECDE approach is used to predict the failure propagation of a selected railway embankment slope at the critical soil moisture or rainfall intensity. This SMECDE failure prediction is validated using relevant data from previous fieldwork and meteorological reports on the critical rainfall intensity at the site. Additionally, the corresponding slope damage scale prediction is validated with a large plastic deformation analysis using the commercial FEM package ABAQUS.

BackgroundThe slope failures triggered by heavy rainfall are challenging to predict. However, their severe impact and potential for extensive damage emphasize the urgent need for effective strategies to mitigate these risks. This study aimed to investigate the effects of pore water pressures (PWPs) and pore air pressures (PAPs) on slope failure during heavy rainfall under centrifuge condition. Three centrifuge rainfall model tests were conducted with varying rainfall intensities (I) and relative densities (Dr). In this experiment, the slope model was subjected to a centrifugal acceleration of 30 G.ResultsIn all cases, slope failures started at the slope toes when the PWPs became positive and phreatic surfaces appeared on the slope surface. In the Toyoura sand case, the PAPs increased slightly at the slope crest, hardly changed at the slope toe, and oscillated at the slope shoulder due to rainwater infiltration. The entire slope failure was observed in this case. In the Silica sand cases, only localized slope toe failures were observed. The PAPs slightly oscillated with small changes in the silica sand case with a relative density of Dr = 50%. However, in the case with a Dr = 25%, the PAPs at the slope toe significantly increased compared to the other parts, and the oscillations were comparatively large. After the first failure occurred at the slope toe in the silica sand case with a Dr = 25%, cracks and slip lines appeared at the slope crest.ConclusionsThe three cases illustrated the complex relationship between soil properties, rainfall intensity, and the dynamics of pore water and pore air pressure on slope stability during heavy rainfall. From the behaviour of PAPs and PWPs in all cases, it was found that the transition from air to water occurred smoothly, and the isolation of air was not observed even during heavy rainfall. Changes in PAPs were far smaller than those in PWPs, indicating a smaller impact on slope stability than PWPs.

Due to climate change, higher rainfall infiltration is expected in the future and it may cause a slope failure. Simultaneously, infrastructure construction and urban redevelopment are rapidly generating large amounts of construction and demolition waste that also contributes to global climate change. To ensure the stability of the slope, it is important to find cost-effective and environmentally sustainable alternatives. Waste material such as recycled concrete aggregate (RCA) can be utilized to protect the slope. The use of RCA for slope protection is that it can be used as a material for the capillary barrier system. The objective of this paper is to investigate the characteristics of pore-water pressure distribution and slope stability with the application of RCA protection during rainfall in comparison with the original slope through numerical modeling. The SWCC for the soil and RCA materials were measured using a high-suction polymer sensor (HSPS) and Tempe cell, respectively. The volume changes of the soil were measured using 3D scanner. SEEP/W was used to conduct the seepage analyses and obtain the change of pore-water pressure distribution due to rainfall infiltration. SLOPE/W was used to evaluate the stability of the slope with different climatic conditions. The use of recycled concrete aggregate (RCA) for slope protection from rainfall infiltration has been investigated in this paper. The results showed that the safety factor of the slope increased with the addition of RCA protection. Rainfall infiltration causes a reduction in soil suction and hence reduces soil shear strength, the safety factor will also decrease since the soil will become weaker.

Due to geological processes such as sedimentation, tectonic movement, and backfilling, natural soil often exhibits characteristics of rotated anisotropy. Recent studies have shown the significant impact of rotated anisotropy on slope stability. However, little research has explored how this rotated anisotropy affects the large deformations occurring after slope failure. Therefore, this study integrates rotated random field theory with smoothed particle hydrodynamics (SPH) to investigate its influence on post-failure slope behavior. Focusing on a typical slope scenario, this research utilizes graphics processing unit (GPU)-accelerated covariance matrix decomposition (CMD) method to create rotated anisotropy random fields and applies the SPH framework for analysis. It examines the influence of rotated anisotropy angles and the cross-correlation between cohesion and internal friction angle on landslides. The results indicate that the rotational anisotropy of the slope significantly influences post-failure behavior. When the rotation angle is close to the slope surface, it tends to amplify both the magnitude and variability of slope failure. Furthermore, the study evaluates the efficiency of generating these random fields and emphasizes the substantial computational speed improvements achieved with GPU acceleration. These findings offer a robust approach for probabilistic analysis of slope large deformations considering rotated anisotropy. They provide a theoretical foundation for accurately assessing the risk of slope collapse, holding significant practical implications for geotechnical engineering.

Slope failures are a significant natural geohazard in hilly and mountainous regions, often resulting in loss of life and infrastructure damage. The Muketuri-Alem Ketema road in Ethiopia is particularly vulnerable to landslides due to colluvial deposits on steep slopes from the higher northeastern plots to the lower Jemma River valley. This study investigates the characteristics of colluvial soil and evaluates the stability of slopes prone to landslides. It combines geophysical data, penetrometer tests, laboratory analyses, Google Earth images, and detailed field visits to assess the soil and bedrock composition and structure. Numerical methods, including limit equilibrium (Bishop, Janbu, Spencer, and Morgenstern-Price methods) and finite element methods, were used to analyze slope sections under various saturation conditions and simulate different rainfall patterns. The results indicate that the Bishop, Morgenstern-Price, and Spencer methods produce similar safety factors with minimal differences (<0.3%), while the Janbu method shows more significant variation (1.5%-5.6%). Safety factor differences for sections A-A and B-B range from 5.26% to 9.86% and 3.5%-4.7%, respectively. Simulations reveal that short-term saturation significantly reduces the stability of the upper slope layer by 20%-46.76%, and long-term saturation decreases the entire slope by 26.81%-46.76% compared to dry conditions due to increased pore water pressure and self-weight. Long-term saturation effects, combined with dynamic loads, can further reduce colluvial soil stability by over 50% compared to a dry static state. The finite element method predicts larger failure zones than limit equilibrium methods, emphasizing the need for accurate predictions to characterize slope behavior during failure and inform stabilization decisions. This study provides crucial data for maintaining and planning the Muketuri-Alem Ketema Road, highlighting slope performance over time and the effectiveness of stabilization techniques.

Purpose - The purpose of this paper is to propose a new combined finite-discrete element method (FDEM) to analyze the mechanical properties, failure behavior and slope stability of soil rock mixtures (SRM), in which the rocks within the SRM model have shape randomness, size randomness and spatial distribution randomness. Design/methodology/approach - Based on the modeling method of heterogeneous rocks, the SRM numerical model can be built and by adjusting the boundary between soil and rock, an SRM numerical model with any rock content can be obtained. The reliability and robustness of the new modeling method can be verified by uniaxial compression simulation. In addition, this paper investigates the effects of rock topology, rock content, slope height and slope inclination on the stability of SRM slopes. Findings - Investigations of the influences of rock content, slope height and slope inclination of SRM slopes showed that the slope height had little effect on the failure mode. The influences of rock content and slope inclination on the slope failure mode were significant. With increasing rock content and slope dip angle, SRM slopes gradually transitioned from a single shear failure mode to a multi-shear fracture failure mode, and shear fractures showed irregular and bifurcated characteristics in which the cut-off values of rock content and slope inclination were 20% and 80 degrees, respectively. Originality/value - This paper proposed a new modeling method for SRMs based on FDEM, with rocks having random shapes, sizes and spatial distributions.

Stronger soil layer within a layered slope is of no concern as the stronger soil layer provides extra stability. But if the relatively stronger soil layer has less permeability, it will cause hindrance to the natural infiltration processes and makes the slope vulnerable. This paper presents the results of a series of laboratory tests and numerical analyses on 45 degrees inclined homogeneous and non-homogeneous unsaturated sandy slopes subjected to continuous rainfall. The non-homogeneous slopes consist of less permeable but stronger silty-sand (NH) layers located at different locations of an otherwise homogeneous sandy soil slope. It is observed that the inclusions of NH layers within the homogeneous sandy slopes trigger a failure during continuous rainfall. The NH layers prevent the seepage of the infiltrated rainwater through the slope. As a result, the water content increases rapidly just above the NH layers and consequently the suction pressures in the soil and its shear strength just above the NH layers decrease. With the rainfall duration, the positive pore water pressures buildup just above the NH layers. This induces a slope failure with the failure plane passing above the NH layer. A discontinuity of the shear plane is also observed in the case of a multiple NH layered soil slope.

The occurrence of rainfall-induced slope failures has become more frequent due to the effect of climate change. Hence, various studies have been conducted to analyse the effect of rainfall infiltration on slope stability. Physically-based hydrological models have been commonly used with slope stability models such as the infinite slope model to develop slope susceptibility maps. However, a combination of three-dimensional (3D) water balance model with 3D limit equilibrium method (LEM) has not been commonly used. Hence, in this study, a water balance model, GEOtop was used to investigate the influence of subsurface flow in unsaturated soil under extreme rainfall conditions on regional slope stability in 3D directions. The results from the GEOtop model were used as inputs for 3D LEM slope stability analysis performed using the Scoops3D software to obtain the factor of safety (FOS) map for the region. Four slopes within the region were then selected to be modelled in the twodimensional (2D) seepage and slope stability analyses, SEEP/W and SLOPE/W. Results from the detailed study showed that the pore-water pressures (PWPs) from the 3D water balance analyses were found to be higher than the 2D seepage analyses. Under similar PWP conditions, the FOS from the 2D slope stability analysis was observed to be lower than the 3D analysis for two out of the four slopes. However, the combined 3D water balance and slope stability analyses produced lower FOS compared to the 2D seepage and slope stability analyses due to the higher PWPs in the 3D water balance analyses. Therefore, this study highlights the importance of considering the 3D subsurface flow in unsaturated soil given that it has a significant influence on the FOS of slopes.