Extreme rainfall causes the collapse of rammed earth city walls. Understanding the depth of rainwater infiltration and the distribution of internal moisture content is crucial for analyzing the impact of rainfall on the safety and stability of these walls. This study focuses on the rammed earth city wall at the Mall site in Zhengzhou. Based on Richards' equation, the water motion equation of rammed earth wall is deduced and established. The change of moisture content of rammed earth wall and the development of wetting front under rainfall condition are studied. The stability of the rammed earth city wall under rainfall infiltration is analyzed by finite element methods. The results show that the water motion equation can effectively describe the moisture distribution inside the rammed earth city wall during rainfall. As the rainfall continues, the wetting front deepens, and the depth of the saturated zone increases. Just below the wetting front, the moisture content decreases rapidly and eventually returns to its initial value. the water motion equation provides a theoretical basis for analyzing water-related damage in rammed earth walls. Factors such as the initial soil moisture content, rainfall duration, and rainfall intensity significantly influence the distribution of the wetting front and moisture content. The saturation of the upper soil layers reduces the shear strength of the shallow soil, leading to a decrease in the safety factor, which can result in shallow landslides and collapse of the rammed earth wall. The research results can provide theoretical support for the analysis of water infiltration law of rammed earth city walls under rainfall conditions, and provide reference for revealing the instability mechanism of rammed earth city walls induced by rainfall. (c) 2025 Elsevier Masson SAS. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Rainwater infiltration will significantly increase the pore water pressure of shallow soil, thus reducing the stability of slope soil. In order to study the migration law of rainwater infiltration wetting front of vegetated slopes, the law of rainfall infiltration was analyzed by using the data of in field monitoring test of slopes. Meanwhile, a vegetated slope infiltration model was established, and the changes in the pore pressure and saturation of the idealized root system on the slope under different rainfall were investigated and analyzed. We found that medium to heavy rainfall (>10 mm/d) can change the shallow water content of vegetated slopes, and light rainfall cannot change the water content; the change in water content of vegetated slopes is less than that of unvegetated slopes under long-duration rainfall, and more than that of unvegetated slopes under short duration rainfall; the change in water content of Ligustrum quihoui Carr. L. shrub slopes are smaller than that of Nerium oleander L. shrub slopes, which has a better effect of slope; under short duration rainfall, the permeability coefficient of root consolidation zone of the vegetated slope is large, the rainwater infiltration speed is fast and it is not easy to cause shallow landslides; with the increase of rainfall time, the plant root system provides a good pore channel, the depth of sudden change of pore pressure of vegetated slope is smaller than that of unvegetated slope. The results of this study provide a reference and analytical basis for vegetated slopes of road graben under rainfall.

The restraining effect of soilbags inhibits soil dilatancy, enhancing the strength and stiffness of the wrapped soil. As a permanent slope protection structure (SSPS), the application of counterpressure enhances stability by improving slope surface stiffness and limiting deformation. While reinforced slopes have been extensively studied, mechanistic investigations into the stability and failure processes of SSPS remain limited. This study numerically investigated the macro-meso mechanisms of SSPS instability using the discrete element method. Macroscopically, rainfall infiltration increases water absorption, resulting in longitudinal settlement, deformation, and eventual instability. With a friction coefficient of 0.5, the lower soilbags resist sliding forces until the front soilbags are damaged. Inadequate sufficient friction causes the front soilbags to be displaced outward, leading to structural collapse as the lower soilbags bear the additional load. Microscopically, geosynthetic wrapping restrains soil dilatancy, promoting tighter particle arrangements and secondary reinforcement through soilbag expansion. During instability, primary contact forces concentrate on longitudinal settlement, vertical back pressure, and downslope sliding, with force chain evolution revealing slip band formation. Soilbags facilitate coordinated particle deformation and stress distribution, transitioning from anisotropic to isotropic states as instability progresses. These findings enhance the understanding of SSPS instability mechanisms, providing guidance for more reliable design and construction practices.

This study examines the impact of rainfall-induced infiltration on the stability of shallow slopes at the open-pit mine in Fuyang, China. The objective was to elucidate the relationship between rainfall, soil moisture, and landslide initiation. Using COMSOL Multiphysics, the research simulated infiltration effects and identified the strongly weathered limestone at +250 m as a critical stability factor. Results showed increased pore water pressure and saturation levels with rainfall, particularly affecting the unsaturated zone. A high-risk landslide area was pinpointed between +250 m and +270 m. To mitigate risks, a reinforcement strategy with mini steel pipe piles was proposed. The study underscores the need for integrated data in predictive models to enhance landslide risk management in mining and other landslide-prone regions.

This study examines the stability of the Huangyukou landslide in Yanqing District, Beijing, under varying rainfall conditions, focusing on the effects of rainfall infiltration and surface runoff on slope stability. Using a combination of field surveys, geophysical methods, drone photogrammetry, and laboratory testing, a high-precision 2D and 3D numerical model was developed. A hydrological-soil-structure coupling model was employed to simulate rainfall-induced infiltration and runoff processes, revealing that increased saturation and pore water pressure significantly reduce shear strength, enhancing the risk of slope failure. Stability analysis, using a reduction factor method, yielded stability coefficients of 1.06 and 1.04 for 20-year and 100-year return period rainfall scenarios, respectively. The results highlight the critical role of rainfall in destabilizing the upper layers of dolomite and shale, with significant deformation observed in the middle and rear slope sections. This research provides a comprehensive framework for assessing landslide risk under extreme rainfall events, offering practical implications for risk mitigation in similar geological contexts.

The South China region is characterized by diverse landforms and significant stratification of geological materials. The rock and soil layers in this area have obvious layering characteristics. The stability of layered slopes is a critical issue in the safe mining of southern ion-type rare earth ores. This study investigates the morphological changes, pore water pressure, and moisture content variation of layered ion-type rare earth ore slopes under the combined effects of rainfall and liquid infiltration through indoor model tests. A numerical simulation was conducted to analyze the variations in pore water pressure, moisture content, slope displacement, and safety factor under different working conditions. As rainfall intensity increases, the interface between soil layers in sandy-silty clay slopes is more likely to form a saturated water retention zone, causing rapid pore water pressure buildup and a significant reduction in shear strength. For the silty-sand clay slopes, the low permeability of the upper silty clay layer limits the infiltration rate of water, resulting in significant interlayer water retention effects, which induce softening and an increased instability risk. The higher the initial moisture content, the longer the infiltration time, which reduces the matrix suction of the soil and significantly weakens the shear strength of the slope. When the initial moisture content and rainfall intensity are the same, the safety factor of the silty-sand clay slope is higher than that of the sandy-silty clay slope. When rainfall intensity increases from 10 mm/h to 30 mm/h, the safety factor of the sandy-silty clay slope decreases from 1.30 to 1.15, indicating that the slope is approaching a critical instability state.

Intense rainfall and extreme modifications to the slope are the immediate triggering factors of landslides and slope instability in the Western Ghats of Kerala, India. An increase in the frequency and intensity of rainfall and its adverse impact on the stability of slopes have demanded slope stability analysis and the adoption of suitable mitigation measures to retard slope failure. This study examines the role of matric suction and pore water pressure variations caused by rainwater infiltration in slope stability. Suction is one of the factors that hold the soil particles together and provide necessary shear strength, hence improving slope stability. During monsoons, water infiltrates the soil which leads to a reduction in soil suction and therein the shear strength and increasing susceptibility to landslides. The study focuses on the rainfall-induced slope failure at Kormala, Muvattupuzha in Kerala, India, where a devastating landslide took place. A laboratory study was conducted on soil samples obtained from the location to obtain the soil properties and soil suction parameters. The resilience of the slope in proximity to Muvattupuzha was assessed numerically for slope stability using a combination of finite element and limit equilibrium analysis software. The variation in pore water pressure across various sections of the slope by varying rainfall intensities was analysed and the change in the factor of safety (FOS) with respect to time at different intensities was compared. The results indicate that infiltration-induced changes in matric suction significantly influence slope stability. At lower rainfall intensities (I = 0.2 Ksat), suction reduction was minimal and the slope remained stable while for moderate intensities (I = 0.4 Ksat and I = 0.6 Ksat), noticeable reductions in suction occurred, particularly near the surface and at the slope toe, leading to a marginal decline in FOS. However, at higher rainfall intensities (I >= 0.2 Ksat), infiltration exceeded the hydraulic conductivity of the soil, causing a rapid decrease in suction and led to near-saturation conditions, especially at the crest and toe sections. Hence, proper and periodic monitoring of the rainfall intensities and soil suction is required for enhanced resilience to slope instability and landslides in this and surrounding regions.

The reduction in the stability of rock slopes due to rainfall is a significant issue in tropical regions. Unsaturated soil, commonly found on hill slopes, provides higher shear strength compared to saturated soil due to matric suction. Soil moisture plays a crucial role in determining slope stability during rainfall events, yet it is often overlooked in geotechnical engineering projects. This study integrates both steady-state and transient analyses to examine how rainfall intensity affects the stability of a rock slope near a tunnel portal. Transient seepage analysis was conducted using SEEP/W to simulate changes in pore water pressure (PWP) resulting from rainfall infiltration under historical and future precipitation conditions. The analysis considers medium (SSP245) and worst-case (SSP585) climate change scenarios as per Coupled Model Intercomparison Project Phase 6 (CMIP6). The findings underscore the significant impact of rainfall-induced infiltration on slope stability and highlight the importance of incorporating soil moisture dynamics in slope stability assessments. The safety factor, initially 1.54 before accounting for rainfall effects, decreases to 1.34 when the effects of rainfall are included.

Soil-water characteristics, which vary with hydrological events such as rainfall, significantly influence soil strength properties. These properties are crucial determinants of the bearing capacity of foundations. Moreover, shear strength characteristics of soils are inherently spatially variable, and considering them as homogeneous parameters can result in unreliable design. This paper presents a probabilistic study of the two-dimensional bearing capacity of a strip footing on spatially random, unsaturated fine-grained soil using Monte Carlo simulation. The study employs the hydro-mechanical random finite difference method through MATLAB programming along with FLAC2D software. The undrained shear strength under saturated conditions is modelled as random fields using a log-normal distribution. The generated random values are then made depth-dependent by correlating them with matric suction. Initially, matric suction is assumed to be under a hydrostatic condition and decreases linearly with depth to zero at the groundwater level. Afterward, unsaturated soil is subjected to rainfall with different durations, resulting in the non-linear distribution of matric suction and, consequently, the mean value of undrained shear strength in depth. The results showed that rainfall infiltration impacts the strength characteristics of near-surface heterogeneous strata, leading to significant effects on the bearing capacity and failure mechanism of footing.

Slope fractures play an important role in slope destabilization accidents induced by rainfall, but its influence on seepage field and slope stability is not fully studied, especially under the conditions of soil permeability anisotropy. This study aims to investigate the influence of anisotropic permeability property of soil and fractures on the seepage field and slope stability under rainfall conditions. The surface cracks of the slope are regarded as continuous medium, and the saturated-unsaturated seepage theory is applied to the numerical simulation of the fractured soil slopes with different anisotropic permeability ratios by Geo-studio software. The evolution of seepage field and slope stability under the rainfall conditions are investigated using finite element simulation tool. The simulation results reveal that fractures mainly impact the pressure distribution in the seepage field of the shallow layer of slope, and have little effect on the deep layer. Furthermore, the anisotropic permeability of the soil has a significant effect on the seepage field, safety factor, and fracture action of the slope under rainfall conditions. These findings provide critical insights into slope engineering and management under anisotropic soil conditions.