开挖前抽水条件下基坑围挡两侧非极限土压力计算模型  

Calculation model of unlimited earth pressure on both sides of enclosure wall during pre-excavation dewatering

作　　者：薛秀丽[1] 刘治珩 曾超峰[1] 白宁 陈宏波 XUE Xiu-li;LIU Zhi-heng;ZENG Chao-feng;BAI Ning;CHEN Hong-bo(Hunan Provincial Key Laboratory of Geotechnical Engineering for Stability Control and Health Monitoring,Hunan University of Science and Technology,Xiangtan,Hunan 411201,China)

机构地区：[1]湖南科技大学岩土工程稳定控制与健康监测湖南省重点实验室,湖南湘潭411201

出　　处：《岩土力学》2024年第6期1699-1708,1719,共11页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51978261);湖南省自然科学基金(No.2022JJ20023);湖南省科技创新计划项目(No.2022RC1172)。

摘　　要：基坑开挖前的坑内抽水可引起围挡发生厘米级的侧移,但现行基坑设计理论仅提出了基于弹性支点法的土方开挖诱发围挡受力变形的计算方法,却并未提出如何计算基坑开挖前抽水引起的围挡侧移。若要沿用弹性支点法进行抽水侧移的计算,则如何确定抽水过程中围挡两侧土压力分布成为关键。为了提出基坑开挖前抽水条件下围挡两侧土压力的计算模型,首先提出了基坑开挖前抽水过程中围挡两侧土体受扰动区形态与范围;然后探明了扰动区内土体应变分布规律并提出土体应变分布模式;进一步地,建立了土体应变与围挡侧移的数学方程,并结合土体应力−应变方程最终构建了开挖前抽水条件下考虑基坑围挡侧移影响的土压力计算模型。所提出的土压力模型能够反映基坑开挖前抽水过程中围挡侧移对土压力的非线性影响,公式形式简单,参数取值方便,可为后续预测抽水引起的基坑围挡侧移提供重要基础。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.

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 

分 类 号：TU46[建筑科学—结构工程]