Numerical Investigation of Rainfall Infiltration-Induced Slope Stability Considering Water-Air Two-Phase Flow

Abstract

For insights into rainfall infiltration on soil slopes and coupled transmission mechanisms, two-phase flow and finite element analysis were employed to examine water and air movement during the Shuping landslide. The results indicated a division of the landslide surface into two zones: an upper inflow area and a lower overflow area, driven by contrasting inflow and outflow directions. The total water and air flux remained stable, minimally affected by external factors such as rainfall attributes, surface runoff, and air temperature variations. In the inflow area of the slope surface, when rainfall intensity was greater than the total rate of the infiltration of water and air, the magnitude of infiltration equalled to the total rate infiltration of water and air, and runoff generation occurred in this area. Conversely, when infiltration matched rainfall intensity, runoff was absent in this area. In addition, water pressure in the saturated area of the slope surface can be transferred to the groundwater of the slope by pore air pressure, which could also increase the pressure head of the groundwater, and this was also detrimental to slope stability. Regarding uniform rainfall, it significantly reduces the safety factor, potentially making it the most hazardous pattern for slope failure.