Water field distribution characteristics under slope runoff and seepage coupled effect based on the finite element method

Abstract

This study examines the influence of preferential flow (PF) on seepage under different rainfall infiltration scenarios, addressing a critical gap in current modeling practices, which often overlook the interactive dynamics between matrix flow (MF) and PF domains within soil environments. In this study, an integrated saturated and unsaturated subsurface flow of dual-permeability (DP) model is developed to calculate seepage and slope stability using pore water pressure. This study aims to conduct numerical experiments of shallow landslides induced by rainfall to quantify the temporal and spatial impact of preferential flow on hydrological mechanisms and slope stability. For low-rainfall intensity, the variation in pore water pressure is greater in the MF domain than in the PF domain. 90 % of rainwater infiltrates downward through the MF domain. Water exchange predominantly occurs in the PF domain, as opposed to the MF domain. The factor of safety decreases from 1.61 to 1.55 when comparing before and after rainfall, which reduces by 3.73 %. For high-rainfall intensity, the pore water pressure variation in the PF domain is more pronounced than in the MF domain. The entirety of precipitation infiltration downwards through the PF domain. Water exchange mainly flows from the PF domain to the MF domain. The factor of safety decreases from 1.61 to 1.45 when comparing before and after rainfall, resulting in a reduction of 9.94 %.