Earth Pressure against Pit-Retaining Structures Rotating around Lateral Supports with a Log-Spiral Failure Surface

Abstract The calculation of earth pressure behind retaining structures rotating about lateral supports in practical pit engineering is systematically investigated in this study through an integrated approach combining theoretical analysis and numerical simulation. An advanced earth pressure calculation model incorporating curved failure surfaces was developed to address this engineering problem. Using finite-element limit analysis, the research elucidates the developmental processes of soil arching phenomena and the progressive formation of nonlinear slip surfaces within the soils. The derivation of solutions for earth pressure distribution was achieved through the implementation of a stratified principal stress trajectory approach, specifically tailored for rotational wall displacements. The results reveal that under lateral support rotation, the soil failure surface exhibits a distinct logarithmic spiral geometry characterized by a horizontal width that first increases and then decreases with depth, and the soil arching effect leads to an R-shaped nonlinear earth pressure distribution. The proposed method successfully captures the transition between the active compression zone (P-zone), the arching-affected zone (U-zone), and the nonarching zone (L-zone). Systematic parameter sensitivity analyses were performed to quantify the impacts of pivotal variables including the rotation center positions, soil internal friction properties, and wall–soil interface characteristics. The developed methodology offers substantial advancements to conventional earth pressure theory by providing a theoretically rigorous yet practical framework for predicting earth pressure distributions under realistic rotational displacement conditions.