Stability Analysis for Three-Dimensional Earth-Retaining Structures Subjected to Rainfall Based on a Modified Green–Ampt Model

Abstract

The active earth pressure of earth-retaining structures (ERSs) is highly dependent on rainfall infiltration. In prior studies, ERS stability was primarily explored based on backfills under unsaturated steady flows or those that were saturated or dry while neglecting the time-dependent properties of the rainfall infiltration procedure. Accordingly, this study assessed the stability of a three-dimensional (3D) unsaturated ERS under diverse modes of rainfall infiltration by exploiting the upper bound theorem of limit analysis. A modified Green–Ampt model was adopted to consider the development of the wetting front; thereafter, an energy equilibrium equation was built to analytically derive the active earth pressure. The effects of the wall friction angle, ERS 3D geometrical characteristics, rainfall infiltration intensity and duration, and rainfall patterns on the active earth pressure coefficient were investigated. According to the results, the wall friction angle and 3D geometrical characteristics lead to a smaller active earth pressure and a superior stability state. The matric suction is a direct determinant of the active earth pressure and stability of the ERS; these exert major effects on the infiltration rate of rainfall into the soil. Furthermore, the rainfall pattern and intensity also have significant impacts on the active earth pressure and the development of the wetting front.