Stability Analysis of Soil Nailing Supporting Structure Based on System Failure Probability Method

摘要

As a popular supporting structure for deep excavation pit or high soil slope, soil nailing has been widely accepted in many civil projects all over the world. In this paper, failure modes of the soil nailing structure are discussed according to its working mechanism and collapsing characters. Global sliding, partly sliding inside the supporting area and pullout of the soil nails are defined as principal failure modes of the supporting system. Considering the randomicity of some parameters of calculation model, such as cohesion, inner friction angle of soil, and friction between soil and nail, failure probability of each failure mode could be computed by using of Monte-Carlo method. System failure probability of the soil nailing structure is determined by using of narrow boundary method, which could be used as an important criterion to analyze stability of the supporting system. Because it has included the influence of some random factors of soil and nailing system, The system failure probability method is better than the traditional safety coefficient method based on limit equilibrium theory. At last, the method is proved to be effective by a real project.