考虑空间效应的均质地基内撑式基坑开挖对邻近桩基影响分析  

Analysis of lateral deformation of adjacent pile induced by braced excavation considering spatial effect in ground of homogeneous soil

作　　者：俞建霖[1,2] 过锦 周佳锦 甘晓露 龚晓南[1,2] 肖方奇 Yu Jianlin;Guo Jin;Zhou Jiajin;Gan Xiaolu;Gong Xiaonan;Xiao Fangqi(Research Center of Coastal and Urban Geotechnical Engineering,Zhejiang University,Hangzhou 310058,China;Engineering Research Center of Urban Underground Development of Zhejiang Province,Zhejiang University,Hangzhou 310058,China;Suzhou CRRC Construction Engineering Co.,Ltd.,Suzhou 215127,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]浙江大学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]苏州中车建设工程有限公司,江苏苏州215127

出　　处：《土木工程学报》2023年第8期140-152,共13页China Civil Engineering Journal

基　　金：浙江省重点研发计划项目(2019C03103)。

摘　　要：基坑开挖引起的坑外土体位移将对邻近桩基产生不利影响。改进原有二维分析方法认为围护墙变形符合平面应变的假定,考虑围护墙变形的空间分布和坑外桩基的空间位置,基于影像源法和Pasternak地基模型,提出了基坑开挖引起的邻近桩基水平位移和弯矩的分析方法,并通过工程实例验证了该方法的合理性。随后基于该方法分析了桩基所处空间位置、桩身刚度和长度、基坑开挖深度、围护墙最大变形等因素对坑外桩基附加变形及弯矩的影响规律,并探讨了诱发坑外桩基变形的围护墙主要影响范围。研究结果表明:(1)坑外桩基所处的空间位置对桩基的附加变形及弯矩存在显著影响,当桩基距离基坑边超过H(基坑开挖深度)时,桩身位移呈悬臂型;(2)随着基坑开挖深度的增加,坑外桩基的水平位移不断增大。桩身最大弯矩先期表现为增加,但当开挖深度大于50%桩长后则表现为减小;(3)坑外桩基的水平位移主要由其两侧各70%H宽度范围内围护墙的变形诱发产生,减小该区域围护墙的变形可以有效控制坑外桩基的附加变形及弯矩;(4)坑外桩基的桩身刚度对基坑开挖引起的桩身弯矩有较大影响,而对桩身变形的影响相对较小。Soil movement induced by excavation may adversely affect the adjacent piles.The original two-dimensional analysis method,which is based on the assumption that the deformation of the diaphragm wall conforms to the plane strain,has been improved.By considering the spatial deformation distribution of the diaphragm wall and the spatial position of the pile outside the foundation pit,and based on the virtual image method and the Pasternak ground model,a method for analyzing the lateral displacement and bending moment of the pile induced by excavation was proposed.The rationality of the proposed method was verified by practical projects.By applying the method,the influence rules of various parameters on pile response were considered,including pile position,pile rigidity and length,excavation depth,and maximum displacement of the diaphragm wall.Furthermore,the main influence range of the diaphragm wall that induces the deformation of the pile is discussed.The results show that:(1)The spatial position of the pile has a significant influence on the additional displacement and bending moment of the pile;when the distance between the pile and the edge of the foundation pit exceeds H(the excavation depth),the displacement of the pile appears to be the cantilever type;(2)The lateral displacement increases with the increase of excavation depth.The maximum bending moment of the pile increases initially,but decreases when the excavation depth is greater than 50%of the pile length;(3)The lateral displacement of the pile is mainly induced by the deformation of the diaphragm wall within the width of70%H on both sides.Reducing the deformation of the diaphragm wall in this area can effectively control the additional deformation and bending moment of the pile;(4)The pile rigidity has a great influence on the bending moment of the pile,while the influence on the displacement of the pile is relatively small.

关 键 词：空间效应 基坑开挖 邻近桩基 影像源法 PASTERNAK地基 

分 类 号：TU473.1[建筑科学—结构工程]