软土地区56 m超深圆形竖井基坑支护结构力学分析  

Mechanical Properties of a 56-m Deep Circular Shaft Foundation Pit Support Structure in Soft Soils

作　　者：宗露丹 王卫东 徐中华 朱雁飞 ZONG Ludan;WANG Weidong;XU Zhonghua;ZHU Yanfei(Shanghai Underground Space Engineering Design&Research Institute,East China Architecture Design&Research Institute Co.,Ltd.,Shanghai 200002,China;Shanghai Engineering Research Center of Safety Control for Facilities Adjacent to Deep Excavations,Shanghai 200002,China;Arcplus Group PLC,Shanghai 200011,China;Shanghai Tunnel Engineering Construction Co.,Ltd.,Shanghai 200002,China)

机构地区：[1]华东建筑设计研究院有限公司上海地下空间与工程设计研究院,上海200002 [2]上海基坑工程环境安全控制工程技术研究中心,上海200002 [3]华东建筑集团股份有限公司,上海200011 [4]上海隧道工程有限公司,上海200002

出　　处：《隧道建设（中英文）》2022年第7期1248-1256,共9页Tunnel Construction

基　　金：上海市科委重点攻关项目(21DZ1204203)。

摘　　要：上海苏州河段深层排水调蓄管道系统工程中的苗圃竖井基坑内径30 m,挖深56.3 m,为软土地区超深圆形基坑工程。为简化施工组织难度、缩短施工周期,通过计算验证分析由原逆作内衬墙方案优化为顺作环梁方案的可行性。采用大型岩土工程有限元软件Plaxis3D,针对该竖井基坑的顺作优化方案,建立考虑土与结构共同作用的三维有限元模型,采用考虑土体小应变特性的HS-Small本构模型,对基坑的开挖进行全过程模拟,验证优化方案的可行性。分析表明:(1)超深圆形基坑的地下连续墙随开挖深度的增加变形逐渐增大,变形形态为“凸肚形”;(2)地下连续墙表现出以环向轴压为主、竖向受弯为辅的受力性状。通过对数值分析结果和工程实测数据的对比,表明地下连续墙的变形及受力性态与实测值较吻合,说明采用小应变本构模型计算分析超深圆形基坑具有较好的适用性。The Miaopu circular shaft foundation pit of a deep tunnel sewerage project in the Suzhou river in the Shanghai soft soil area has an inner diameter and excavation depth of 30 m and 56.3 m,respectively.To simplify the construction logistics and shorten the construction period,the feasibility of replacing the inner lining wall scheme of down-top ring beam by one using a top-down ring beam is investigated in this paper using numerical simulations.The Plaxis 3D software is employed to establish a three-dimensional finite element model considering the soil-structure interaction.The HS-Small constitutive model considering small strains that develop in soil is used to simulate the entire excavation process of the foundation pit.The analytical results reveal that the deformations of the circular diaphragm wall increase with an increase in excavation depth and present a spindle type.The diaphragm wall is mainly subjected to circumferential axial compression supplemented by vertical bending.A comparison between the simulation results and monitoring data shows that the deformations and stresses predicted by the model agree well with the monitoring results,indicating a good applicability of the proposed model in analyzing the circular shaft foundation pit.

关 键 词：超深圆形基坑 软土 三维有限元模拟 HS-Small模型 变形性状 

分 类 号：U45[建筑科学—桥梁与隧道工程]