Displacement and force analyses of braced structure of deep excavation considering unsymmetrical surcharge effect

Abstract

This paper describes the displacement and force behavior of a braced deep excavation under unsymmetrical surcharge effect. The horizontal displacements and bending moments in diaphragm walls, bending moments and axial forces in amplitude modulation (AM) piles, and lateral ground movements were analyzed employing the finite difference (FD) method. The FD method was validated by yielding wall displacements and bending moments matching closely the results of the beam on elastic foundation method and the field monitoring data. It was found that the surcharge effect was detrimental to the wall and pile responses and the excavation stability. The wall displacements reached maxima at depths slightly above the final excavation bottom due to the principal stress rotation resulting from the surcharge effect. The maximum wall bending moments developed at a depth which was independent of the final excavation depth. The depths at which the maximum axial pile forces developed increased with progressing the stage of excavation. The lateral ground movements were deteriorated by the unsymmetrical surcharge load, guiding the design and optimization of the excavation bracing system for minimizing the adverse effects on the adjacent structures.