Probabilistic Analysis of a Braced Excavation Considering Soil Spatial Variability

Deep braced excavations are generally known to be associated with risks from various sources. The inherent uncertainty of soil strength properties is one of the primary factors that influence the deformation of the retaining wall and the ground settlement. In this study, the numerical model of a braced excavation is firstly established by an elastic-plastic model with Drucker-Prager failure criterion in COMSOL Multiphysics. Random field theory is used to simulate the spatial variability of Young's modulus. The uncertainty of braced excavation on ground settlement and deflection of retaining wall by stages are studied by Monte Carlo simulation based on 500 random fields. The struts can lessen the uncertainty of wall deflection during excavation but have a limited impact on settlement. The deterministic result may underestimate the settlement of braced excavation. The uncertainty of wall deflection is significantly reduced after the first strut. The uncertainty of wall deflection above the depth of struts is well-controlled at the final stage of excavation.