基坑开挖及降水引起下卧隧道变形的解析解  

Analytical solution of deformation of underlying shield tunnel caused by foundation pit excavation and dewatering

作　　者：管凌霄 徐长节[1,2,3] 王雪鹏 夏雪勤 可文海 GUAN Ling-xiao;XU Chang-jie;WANG Xue-peng;XIA Xue-qin;KE Wen-hai(State Key Laboratory of Performance Monitoring Protecting of Rail Transit Infrastructure,East China Jiaotong University,Nanchang,Jiangxi 330013,China;Engineering Research&Development Centre for Underground Technology of Jiangxi Province,East China Jiaotong University,Nanchang,Jiangxi 330013,China;Jiangxi Key Laboratory of Infrastructure Safety Control in Geotechnical Engineering,East China Jiaotong University,Nanchang,Jiangxi 330013,China)

机构地区：[1]华东交通大学轨道交通基础设施性能监测与保障国家重点实验室,江西南昌330013 [2]华东交通大学江西省地下空间技术开发工程研究中心,江西南昌330013 [3]华东交通大学江西省岩土工程基础设施安全与控制重点实验室,江西南昌330013

出　　处：《岩土力学》2023年第11期3241-3251,共11页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.52238009);江西省自然科学基金(No.20224BAB214068);江西省研究生创新资金(No.YC2021-S433)。

摘　　要：基坑开挖及降水打破周围土层的平衡应力场,对下卧盾构隧道造成不良影响。采用两阶段分析法提出了基坑开挖及降水共同作用引起的下卧隧道纵向变形解析解。在第1阶段采用Mindlin弹性解与有效应力原理分别计算出基坑开挖与降水对下卧隧道造成的附加应力;第2阶段将盾构隧道视为Timoshenko梁搁置在Pasternak地基模拟隧道与土的相互作用,通过叠加法推导出隧道纵向变形解析解。通过与工程实例监测数据的对比,验证了方法的正确性,并进一步分析了基坑开挖长度、宽度、深度、隧道埋深、水位降深及与基坑相对位置等因素对隧道纵向位移的影响。结果表明:随着基坑开挖长度、宽度和深度的增加,隧道最大隆起值均明显增大;隧道变形随着隧道埋深的增加而减小;坑内水位降深的增加将导致隧道隆起值减小而沉降值增大;随着隧道轴线与基坑中心距离的增加,可依次为隆起值减小区、沉降值增大区及沉降值减小区。The foundation pit excavation and dewatering break the equilibrium stress field of the surrounding soil layer and negatively affect the underlying shield tunnel.The analytical solution of the longitudinal deformation of the underlying tunnel caused by foundation pit excavation and dewatering is proposed using a two-stage analysis method.In the first stage,Mindlin elastic solution and effective stress principle are used to calculate the additional stress caused by excavation and dewatering.In the second stage,the shield tunnel is treated as a Timoshenko beam resting on the Pasternak foundation to simulate the interaction between the tunnel and soil.The analytical solution of the longitudinal tunnel deformation is derived from the superposition method.By comparing with the monitoring data of engineering examples,the correctness of the proposed method is verified,and the influence of the excavation length,width,depth,tunnel burial depth,dropdown,and relative position of the foundation pit on the longitudinal displacement of the tunnel is further analyzed.The results show that with the increase of excavation length,width,and depth,the maximum uplift of the tunnel increases.The tunnel deformation decreases with the increase in tunnel burial depth.With the increase of the dropdown,the uplift decreases,and the settlement value increases.With the increased distance between the tunnel axis and the foundation pit center,there are a decreasing area of the uplift,an increasing area of the settlement,and a decreasing area of settlement.

关 键 词：基坑开挖 基坑降水 下卧隧道 剪切变形 TIMOSHENKO梁 PASTERNAK地基 

分 类 号：TU463[建筑科学—结构工程]