杭州软黏土地区某30.2m深大基坑开挖性状实测分析  

Performance analysis of a 30.2m deep-large excavation in Hangzhou soft clay

作　　者：程康 徐日庆[1,2] 应宏伟 李冰河[5] 甘晓露 裘志坚[6] 詹晓波 秦建设 CHENG Kang;XU Riqing;YING Hongwei;LI Binghe;GAN Xiaolu;QIU Zhijian;ZHAN Xiaobo;QIN Jianshe(Research Center of Coastal and Urban Geotechnical Engineering,Zhejiang University,Hangzhou,Zhejiang 310058,China;Engineering Research Center of Urban Underground Development of Zhejiang Province,Hangzhou,Zhejiang 310058,China;China Railway 11th Bureau Group Co.,Ltd.,Wuhan,Hubei 430061,China;Institute of Geotechnical Engineering Science,Hohai University,Nanjing,Jiangsu 210098,China;Zhejiang Province Architectural Design and Research Institute,Hangzhou,Zhejiang 310058,China;Hangzhou Metro Group Limited Company Co.,Ltd.,Hangzhou,Zhejiang 310020,China;Zhongtian Construction Group Co.,Ltd.,Hangzhou,Zhejiang 310020,China)

机构地区：[1]浙江大学滨海和城市岩土工程研究中心,浙江杭州310058 [2]浙江省城市地下空间开发工程技术研究中心,浙江杭州310058 [3]中铁十一局集团有限公司,湖北武汉430061 [4]河海大学岩土工程科学研究所,江苏南京210098 [5]浙江省建筑设计研究院,浙江杭州310058 [6]杭州地铁集团有限责任公司,浙江杭州310020 [7]中天建设集团有限公司,浙江杭州310020

出　　处：《岩石力学与工程学报》2021年第4期851-863,共13页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(41672264);浙江省重点研发计划项目(2019C03103);浙江省住房和城乡建设厅建设新技术、新产品研制和推广项目。

摘　　要：以杭州某30.2m深大基坑工程为研究对象,结合收集到的16个杭州基坑案例资料以及文献中已发表的上海地区同类工程实测数据,分析该30.2 m深大基坑开挖全过程中的地连墙隆沉及挠曲变形、地连墙墙体应力、立柱隆沉、支撑轴力、土压力、地表沉降等的发展演变规律。得出如下结论:(1)地连墙最大侧移深度Hm在Hm=He-5和Hm=He+2.5之间。受益于围护体系良好的整体性,基坑地连墙的最大侧移δhm得到了较好地控制,平均最大侧移为0.28%He。(2)位于开挖中部的地连墙侧移是坑角附近的3.5倍,这主要是"坑角效应"所致,可见对未采用分区开挖的深大基坑,坑角的"加筋"作用对限制开挖变形非常重要。(3)受杭州软黏土"蠕变效应"和深开挖"深度效应"的影响,地连墙和坑外地表在阶段6均产生了最大位移增量。深埋土层较浅埋土层的开挖会释放更多的应力,诱发更大的变形。(4)水平支撑主要承担由邻近土层移除所产生的外荷载,较远处的开挖对支撑轴力影响有限,且由开挖引起的外荷载向支撑的转移主要在支撑浇筑后的1~2个月内完成。(5)不同于梯形或AEP三角形包络线分布,本工程地连墙墙后水平土压力沿深度呈线性分布。靠近开挖面的地基土,更容易处于主动状态,产生较小的水平土压力。(6)基于本30.2 m深大基坑实测数据以及杭州16个类似的基坑案例,提出了基于基坑开挖面积与地连墙最大侧移之间的经验关系式。Taking a 30.2 m deep and large basement excavation in Hangzhou soft clay as the research object,the excavation performances,including the stress of diaphragm walls,the displacement of columns,the axial force,the earth pressure and the settlements of ground surface,are thoroughly investigated based on 16 excavation cases collected in Hangzhou and the data published in literature about similar excavation in Shanghai. Following conclusions are obtained:(1) The location of the maximum wall deflection is between He-5 and He + 2.5. Benefiting from the excellent integrity of the retaining system,the maximum wall deflection is well controlled with an average value of 0.28%He.(2) Due to the"corner effect",the deflection of the walls located at the excavation center is 3.5 times of that located at the corners,suggesting that the"corner effect"is significant to restrict the deflection for the excavation without adopting the zoned excavation technique.(3) Both the diaphragm walls and the ground surface produce a maximum displacement increment in stage 6 due to the"creep effect"of Hangzhou soft clay and the "depth effect" of deep excavation. The excavation of deep soil can release more stress and induce greater displacement than shallow soil.(4) The horizontal struts mainly carry the load due to the removal of the nearby soil and are slightly influenced by the distant excavation. The transferring of the excavation-induced load to the struts is completed in 1–2 months after strut casting.(5) Different from trapezoid or AEP triangle envelope distribution mode,the horizontal earth pressure behind the diaphragm wall of the considered project is linearly distributed along the depth. The ground adjacent to the excavation surface is more likely in an active state and generates smaller horizontal earth pressure. Based on the 30.2 m deep excavation and the collected 16 similar excavation cases in Hangzhou,an empirical relation between the excavation area and the maximum wall deflection is proposed.

关 键 词：基坑工程 深大开挖 挡墙挠曲 蠕变效应 坑角效应 开挖面积 

分 类 号：TU473[建筑科学—结构工程]