软土地区超深圆形竖井的坑底隆起特性与机制  

Characteristics and mechanism of soil heave at the bottom of ultra-deepcircular shafts in soft soil areas

作　　者：乔亚飞[1,2] 闫凯 赵腾腾 丁文其[1,2] QIAO Ya-fei;YAN Kai;ZHAO Teng-teng;DING Wen-qi(Department of Geotechnical Engineering,College of Civil Engineering,Tongji University,Shanghai 200092,China;Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Tongji University,Shanghai 200092,China;Shanghai Municipal Engineering Design Institute(Group)Co.,Ltd.,Shanghai 200092,China;Engineering Project Management Company,Shanghai Chengtou Water Group,Shanghai 200002,China)

机构地区：[1]同济大学土木工程学院地下建筑与工程系,上海200092 [2]同济大学岩土及地下工程教育部重点实验室,上海200092 [3]上海市政工程设计研究总院(集团)有限公司,上海200082 [4]上海城投水务工程项目管理公司,上海200002

出　　处：《岩土力学》2023年第9期2707-2716,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金重大项目课题(No.52090083);上海市晨光计划项目(No.20CG26);上海市苏州河深隧项目横向课题。

摘　　要：依托上海某超深圆形竖井工程,收集了施工期坑底土体隆起的实测数据,总结了坑底土体隆起的竖向分布模式、演变规律和主要影响因素;建立并验证了轴对称数值模型,探讨了开挖卸荷、降水、地下连续墙和土体力学特性对坑底土体隆起的影响规律,探明了坑底土体的隆起机制。土体隆起是开挖卸荷、降水和地下连续墙约束作用下土体力学响应的综合结果,其中开挖卸荷和墙体挤压会引起隆起,降水和墙体的负摩阻力会抑制隆起。开挖卸荷存在主要影响深度,卸荷回弹主导了该深度范围内土体的隆起,而土体剪切变形则控制了该深度范围外的土体隆起。土体流变以及负孔隙水压的消散共同导致了土体隆起的时间依赖性。软土地区小直径超深竖井的坑底隆起沿深度方向减小近似线性,最大值位于开挖面中心处;土体隆起随开挖先缓慢增加后近似线性快速增大,而在非开挖阶段,土体隆起随时间有缓慢增大趋势。Based on an ultra-deep circular shaft project in Shanghai,the field data of soil heave at the bottom of the pit during the construction were collected,and the vertical distribution pattern,evolution law and main influencing factors of soil heave at the bottom of the pit were summarized.An axisymmetric numerical model was then built and verified to investigate the effect of the excavation-induced unloading,dewatering,diaphragm wall and soil mechanical properties on the soil heave,then the mechanism of soil heave was revealed.Soil heave was the combined result of the soil mechanical response under the excavation-induced unloading,dewatering,and diaphragm wall restraint,in which the excavation-induced unloading and the deflection of the diaphragm wall caused the soil heave,and the dewatering and the negative frictional resistance inhibited the soil heave.Excavation-induced unloading had a prominent influence on the depth,and the unloading rebound mechanism dominated the soil heave within that depth,while the shear deformation controlled the soil heave beyond that depth range.Soil rheology and dissipation of negative pore water pressure jointly led to the time dependence of soil heave.The soil heave at the pit bottom of small-diameter ultra-deep shafts in soft soil areas decreased approximately linearly along the depth,and its maximum value was located at the center of the excavation face.The soil heave first increased slowly and then increased near linearly and rapidly with the increase of excavation depth.However,the soil heave tended to increase slowly with time in the non-excavation stage.

关 键 词：超深圆形竖井 土体隆起 机制 监测数据 数值模拟 

分 类 号：TU443[建筑科学—岩土工程]