Model test study on horizontal soil arching effect in pile-supported retaining structures

Abstract This study aims to investigate the load transfer mechanism between piles and soil and the evolution of horizontal soil arching effect during the excavation of pile-supported retaining structures in deep excavations. A series of model tests with staged excavation was systematically designed to examine the effects of excavation depth, pile width, and net pile spacing on horizontal soil arching effect. The investigation also tracked changes in lateral earth pressure coefficients and monitored crack propagation patterns in the soil behind piles. The evolution of the soil arching process was classified into three stages: (1) the excavation loosening stage, (2) the soil arching load transfer stage, and (3) the soil arching degradation and failure stage. Excavation depth is a critical factor influencing the soil arching effect, while a well-optimized combination of pile width and net pile spacing can maximize the effectiveness of soil arching. These findings offer practical insights for optimizing pile-supported retaining structures in deep excavation projects.