Numerical study on performance of waterfront excavation

A two-dimensional finite element method (FEM) simulation is carried out to investigate the performance of the retaining structure scheme, including the conventional diaphragm wall and the recommended concrete-filled double-row composite steel sheet piles, for a waterfront braced excavation project. Representative numerical models based on Plaxis 2D are established to compare the differences of lateral displacement, safety factor of stability, and internal force of retaining structures under complicated construction and loading conditions. The numerical results reveal that the composite steel sheet piles can be constructed simultaneously with the front pile-supported wharves in water to exhibit the greater global bending stiffness of concrete combined with the steel sheet piles more effectively, reducing the lateral soil pressure acting on the retaining wall correspondingly during inside excavation and dewatering. Therefore, the maximum lateral displacement of the composite steel sheet piles is only around one third that of the diaphragm wall at the most disadvantageous construction stage, and the overall deformation as well as the stability characteristics are better than those of the diaphragm wall, demonstrating a favorable load-carrying performance and a vigorous deformation control capability.