关键词: 基坑围挡位移, 开挖前降水, 应变状态模式, 应力路径, 非极限土压力

Abstract: Pre-excavation dewatering (PED) can induce centimeter-level movements in the enclosure wall. Current foundation pit design theory only proposes a calculation method for excavation-induced force and deformation of the enclosure wall based on the elastic fulcrum method, which does not address PED-induced wall deflections. To continue using the elastic fulcrum method for calculating PED-induced wall deflections, it is crucial to determine the distribution of earth pressure on both sides of the enclosure wall during PED. This study aims to propose a novel model for calculating the PED-induced earth pressure on both sides of the enclosure wall. First, we analyzed the shape and influence range of disturbed soil on both sides of the enclosure wall during PED. Then, we explored the characteristics of soil strain distribution in the disturbed zone and proposed a distribution mode for the soil strain. Furthermore, we established a mathematical equation presenting the relationship between the soil strain and enclosure wall deflections, and proposed a calculation model of earth pressure considering the wall deflections during PED. The proposed calculation model accurately reflects the nonlinear relationship between wall deflections and earth pressure during PED. The obtained model, with its simple formulation and easily available data, could provide an important reference for predicting PED-induced enclosure wall deflections.

Key words: enclosure wall deflection, pre-excavation dewatering, strain state mode, stress path, non-limit state earth pressure