Slope stability analysis under heavy rainfall considering the heterogeneity of weathered layers

In the analysis of slope stability under heavy rainfall, the results of numerical simulations may yield a safety factor greater than 1 while the actual slope failure still occurs. This discrepancy may arise because the physical and mechanical parameters of the slope used in the calculation are uniform values without considering the heterogeneity of the actual slope material. This study introduces the Weibull distribution to simulate the heterogeneity of weathered layers in slopes. Based on this approach, detailed numerical simulations of unsaturated–saturated seepage and slope stability were conducted using the FLAC^3D code. Based on the built-in function of uniform random distribution in FLAC^3D, the Weibull distribution of elastic modulus E and cohesion c of weathered layers can be implemented through the secondary development of program using FISH functions. Laboratory tests were carried out to determine the soil water retention curve. A case representing different degrees of heterogeneity in weathered layers based on the application of Weibull distribution was modeled. The results show that considering the heterogeneous weathered layers under heavy rainfall reflects better the real conditions of the slope and represents a more accurate approach.