Active Earth Pressure From Unsaturated Soils With Displacement Modes of Rigid Retaining Wall Under Rainfall Conditions

ABSTRACT This study proposes a unified analytical framework for unsaturated active earth pressure to evaluate retaining wall stability under transient rainfall infiltration. The framework incorporates three critical wall displacement modes: translation (T), rotation about the top (RT), and rotation about the base (RB). Guided by finite element analyses that systematically characterize the evolution of principal stress trajectories and failure surface morphologies under each mode, an analytical solution is derived. This solution integrates an extended Mohr‐Coulomb strength criterion, a generalized wetting front infiltration model, and an inclined‐slice limit equilibrium approach featuring an interlayer shear coefficient to quantify inter‐slice shear forces. Experimental and numerical validations confirm the method's reliability. Parametric studies demonstrate that a deepening wetting front increases the lateral active earth pressure and the overturning moment on the retaining wall, thereby significantly reducing stability. The applicability of the resultant force acting at one‐third of the wall height is governed by the combined effects of wall displacement modes, soil matric suction, slope inclination, and wall‐soil interface friction angle. This methodology establishes a theoretically rigorous yet practical tool for stability assessment under extreme rainfall events, offering crucial insights for engineering design optimization.