Stability Analysis of Soil Excavation by 3D FEM

An elastoplastic shear strength reduction FEM is used to analyze the 3D stability of the excavation slope.For the excavation slope with the weak constraint condition,the location of the initial failure plane is in the middle of the slope.With the increment of the factor of strength reduction,the slope failure zone is extended to the sides of the slope.When the ratio of the excavation length to the height is more than 4,the factor of safety of the slope less affected by constrained boundaries is approximately the same as that of plane strain stability analysis.For the excavation slope with the obvious corner effect, each section of the slope almost reaches failure simultaneously.The factor of safety of the slope is larger than that of plane strain stability analysis.If the above problem is analyzed by the 2D plain strain method,the result will be conservative for the design of project.