Numerical Analyses on Wall Deflections and Ground Surface Settlements in Excavations

Ground movements may cause damages to structures. Accurate estimations of ground movements are therefore essential for the risk assessment programs for projects involving underground constructions. Presented herein is a study on the influence of various parameters on the magnitudes and the distributions of ground movements during deep excavations with emphasis on the shapes of settlement troughs. Two-dimensional finite element analyses were conducted on 5 cases for the east end of Xiaonanmen Station in Taipei Metro. The hardening soil with small-strain stiffness was adopted to simulate the nonlinear stress-strain relationship of soils. The results indicate that the shapes of the settlement troughs are primarily affected by the depths of excavations and are relatively insensitive to the width of excavation or the thickness of the retaining wall. Based on the results obtained, the relationship between the width of the influence zone of settlement and the depth of excavation is established.