局部超挖对内支撑结构的施工效应

打开文本图片集

中图分类号：TU473；TB115.1 文献标志码：B

Construction effect of partial over-excavation on inner-support structure

WEI Huanwei1a，1b，1c，LI Chuanbin1a， CHONG Jixin2， ZHENG Xiaola，1b，1c （1.a.School of Civil Engineering；b.KeyLaboratory of Building Structural Retrofitingand Underground Space Engineering（Ministry of Education）；c. Subway Protection Research Institute，Shandong Jianzhu University，Jinan 250101，China；2. Jinan Rail Transit Group Co.，Ltd.， Jinan 25O100，China）

Abstract：In order to determine the local over-excavation amount during excavation of foundation pits and control the construction efects of local over-excavation，based on the analysis of measured data，the PLAXIS 3D numerical analysis software is used to simulate and analyze the stressand deformation characteristics of the supporting structure under diffrent partial over-excavation ranges，to study the construction efect range of partial over-excavation on the support structure. Then，on the premise of fixed foundation pit width，a method to determine the optimal local over-excavation range is proposed. The results show that，partial over-excavation willhave obvious construction efects on the over-excavated area and the adjacent non-over-excavated area，including the lateral displacement， bending moment，and support axial force of the supporting structure. As the area of partial over-excavation increases，the internal force and lateral displacement of adjacent areas also gradually increase，and the range of influence has a certain relationship with the range of partial over-excavation. The earth presure behind the pileis greatly reduced in the over-excavation area.For the effect of soil arching and loading，the earth pressure in the adjacent non-over-excavated area will rise slightly. Key words： deep foundation pit；partial over-excavation； law of deformation； numerical simulation； construction efcts ； bending moment and axial force ； earth pressure； influence range

0引言

局部超挖可定义为在未架设某层支撑时，分层开挖至该层内支撑设计位置并继续向下开挖一段深度，然后再进行架设支撑[1]。（剩余10600字）