Numerical modeling of small-scale unsaturated soil slope subjected to transient rainfall

• Main Authors: Liu, Chang, Yan, Yipu, Yang, Haoqing
• Other Authors: School of Civil and Environmental Engineering
• Format: Article
• Language: English
• Published: 2024
• Subjects: Engineering; Slope; Rainfall
• Online Access: https://hdl.handle.net/10356/173655
• Institution: Nanyang Technological University

Climate change is creating more extreme rain events and causing more landslides in recent years. Most of the previous studies focused on large-scale slopes such as mountainous areas. For the problem of small-scale landslides in urban areas, a hydro-mechanical analysis of soil slopes under rainfall is also demanded. In this study, a numerical model of a slope under rainfall and load is established by COMSOL Multiphysics. To facilitate the analysis for practical purposes, two built-in modules are used to model a unidirectional coupling of hydro-mechanical behaviors of unsaturated soil slopes. The Richards’ module is first adopted to model an unsaturated soil slope under rainfall. Then the Extended Barcelona Basic module that considers the matric suction is adopted as the constitutive model. The effect of rainfall duration and saturated hydraulic conductivity on stress, settlement, and pore-water pressure are studied. When the rainfall proceeds, the matric suction head keeps reducing constantly. For a fixed location, the settlement decreases as ks increases. The wetting front is more apparent as the ks is reduced as the curvature of the pore pressure profile is more pronounced. The matric suction at a steady state is decreased when the ks becomes small. The simulated soil suction is comparable to these field monitoring data.