Comprehensive hydromechanical analysis of unsaturated heterogeneous slopes in the Tébessa region

Abstract

Landslides, triggered by the loss of soil cohesion, necessitate a thorough understanding of soil hydrological properties, particularly concerning rainfall. This study employs FLAC software for numerical modeling to examine a slope in the Tebessa region, focusing on the effects of precipitation infiltration, suction profiles, and slope heights on the safety factor. The hydraulic characteristics of unsaturated soil are represented using the van Genuchten equations. Initial analyses combine hydromechanical assessments across various soil layers to understand how rainfall infiltration influences deformation and pore-water pressure, thereby affecting slope stability. Stability evaluations are conducted before and after rainfall events. A second part of the study compares the results of the finite difference method (FDM) and the finite element method (FEM) using FLAC and PLAXIS software. To achieve an effective comparison, we explored various methodologies for analyzing two-dimensional slope models using different soil types exposed to varying precipitation levels. Coupled simulations, enabled by the two-phase flow option, are used to evaluate the stability of slopes in the unsaturated state. The validity of these methods is assessed by altering soil types and examining how varying suctions for each soil, hydraulic conductivity, and precipitation influence the safety factor.Results highlight the necessity of considering surface runoff infiltration and incorporating comprehensive soil layer attributes for accurate slope stability modeling. Discrepancies between the software packages at high suction values are noted, with FLAC being more conservative and superior in representing unfavorable conditions.