Deformation and Force Analysis of the Pile Foundation System of Deep Foundation Pits in Soil–Rock Combination

Abstract

This study uses the construction of the Shengli Bridge Station of Qingdao Metro Line 1 as the engineering support for in-depth research of the deformation and mechanical characteristics of the retaining structure of pile-support systems during deep foundation pit excavation under the complex geological conditions of soil–rock combination. This study adopts the finite element software modeling analysis method to simulate the excavation of the foundation pit and the 3D finite element numerical calculation method to calculate the deformation. The modified Mohr–Coulomb model is selected as the constitutive model, and the natural gravity of each layer of soil is considered. The calculated load includes the dead load of structure and soil. The boundary conditions of X, Y, and Z directions at the bottom are fixed constraints, and the top ground is a free boundary. The displacement of soil around the foundation pit and the stress and deformation of retaining piles and crown beams under different working conditions are studied. The deformation law and force mechanism of the supporting structure of the pile-support system are analyzed. The research results reveal the relationship between the synergy of pile-support system and soil deformation, serving as a reference for similar engineering constructions.