Influence of Rainfall Intensity on the Stability of Unsaturated Soil Slope: Case Study of R523 Road in Thulamela Municipality, Limpopo Province, South Africa

Abstract

The purpose of this paper was to analyze the impact of extreme rainfall on the recurrence of slope instability using the Thulamela Municipality roads (R523) as a case study. To this end, the historical rainfall data of the area of study were analyzed between 1988 and 2018. The results show that a significant increase in rainfall is usually experienced in the summer months of December and January. Following this, the factor of safety (FoS) of slopes of silt clay, clay, and clay loam soils were estimated using the SLIDE simulator (Numerical software “Finite Element Method (FEM)”) under sunny to rainy conditions of the area. A complementary model, FLACSlope (Numerical software “Finite Difference Method (FDM)”), was utilized to simulate FoS and pore water pressure in sunny and rainy conditions of the area. Simulation results show that extreme rainfall has the ability to reduce the shear strength and resistance of the soil slope material. This may explain the recurrent landslides noted in the area. Finally, the water pore pressure has been simulated to increase with the increased water table, which generally pushes the soil particles apart and reduces the stress between the particles resulting in soil slope failure. Extreme rainfall alters the phase of the material solid in a manner that may require further research for a better understanding.

Establishing Reliable Slope Stability Hazard Map Based on GIS‐Based Tool in Conjunction with Finite Element Methods

“…is is because the exercise determined how realistic the computer model of the actual rock mass associated with the study area would be. For a thorough interpretation of the results, several methods (Bishop simplified, Corps of Engineers' #1 and 2, the GLE/ Morgenstern Price method, Janbu's simplified and corrected Lowe-K aralias, Ordinary, and Spencer) of analysis were considered (see studies such as [29,30,[32][33][34][35][36]). e motivation was to compare various approaches to the problem while corresponding results were interpreted based on the performance of each approach.…”

Slope Stability Analysis to Correlate Shear Strength with Slope Angle and Shear Stress by Considering Saturated and Unsaturated Seismic Conditions

“…It is observed that an increase in the water table will also increase water pore pressure, which pushes the soil particles away from each other, and hence reduces the stress between the particles resulting in soil slope failure. Two such papers [34,35] may be used as a guide to finding the adequate literature on the most used or the most advanced approaches followed in every step of the procedure for defining reliable rainfall thresholds. Figure 7 presents the factor of safety values achieved in the case of Material 1 for slope angle ranges from 70 to 88 degrees, respectively.…”

Design of Cost-Effective and Sustainable Treatments of Old Landslides Adapted to the Moroccan Road Network: A Case Study of Regional Road R410 Crossing the Rifan Structural Domain

“…In addition, several researchers [24][25][26][27][28][29][30][31] have examined the application of physical or empirical models on the impact of precipitation on slope stability. Most of them claimed that the effects of meteorological, morphological, and geological characteristics were mitigated.…”