Mechanical and deformation characteristics of composite assembled supporting structure

Abstract

The composite assembled recyclable supporting structure is a type of newly developed supporting structure; it combines a steel skeleton supporting structure with polymer waterproof technology. Based on the Niukouyu excavation project in Zhengzhou, China, a three-dimensional finite-element model is established to simulate the excavation process using this type of supporting structure. The effects of important design factors (foundation pit depth, length-to-width ratio and steel beam interval) on lateral displacements and bending moments of the supporting pile in the worst scenario are analysed. The results show that the composite assembled recyclable supporting structure can effectively control the deformation of the excavation. The supporting pile has an inward deformation mode. Both maximum lateral displacement and bending moment occur at about 0.8H e (where H e is the foundation pit depth) below the ground surface. The maximum lateral displacement of the supporting pile ranges from 0.023% H e to 0.12% H e. Furthermore, a global sensitivity analysis is also conducted to distinguish the relative importance of uncertain soil parameters (elastic stiffness and shear strength) on the system behaviour in this Niukouyu project. It is found that the elastic modulus of soil dominates the supporting structure responses, while the soil shear strength plays an insignificant role in determining the system behaviour due to negligible plastic deformations.