Stability Analysis for Cofferdams of Pile Wall Frame Structures: Fid-Bau Portal

Stability Analysis for Cofferdams of Pile Wall Frame Structures

Xue, Runze / Bie, Shean / Guo, Linlin / Zhang, Peiliang

Abstract Pile wall frame structures (PWFSs) are double-wall sheet-pile structures with an integrally precast framework of reinforced concrete to connect double rows of closely placed piles. An engineering test on a cofferdam of PWFSs was conducted in Binzhou, where lateral displacement along pile shaft was carefully monitored during the hydraulic filling process. A 3D finite element model (FEM) of the test was established to study the stability failure mechanism of PWFSs. Then, a design method for PWFSs was proposed through a structural stability analysis based on the limit equilibrium method, with special consideration of the cutting pile force influenced by row spacing. According to FE results, lateral pile displacements drawn from the FEM correspond well with field observations, and earth pressures applied on closely spaced piles are in line with Rankine’s theory. Results of the theoretical analysis indicate that the control slip surface lies on the bottom of a soil layer with a poorer shear strength index. The effects of framework width, pile spacing, pile length and diameter on structural stability are also evaluated. The feasibility of PWFSs has been verified by an engineering test, and the simplified design method established here is reasonable and effective for structural stability prediction.