桩锚支护基坑对近邻建筑影响实测及三维数值分析  

Numerical analysis and filed monitoring on deformation characteristics of deep excavation adjacent to building with shallow foundation

作　　者：谭鑫[1,2] 金永乐 黄明华 刘晓明 胡政博[1] 陈大川 Tan Xin;Jin Yongle;Huang Minghua;Liu Xiaoming;Hu Zhengbo;Chen Dachuan(College of Civil Engineering,Hunan University,Changsha 410082,China;Key Laboratory of Building Safety and Energy Efficiency of the Ministry of Education,Hunan University,Changsha 410082,China)

机构地区：[1]湖南大学土木工程学院,湖南长沙410082 [2]湖南大学建筑安全与节能教育部重点实验室,湖南长沙410082

出　　处：《土木工程学报》2023年第7期126-136,共11页China Civil Engineering Journal

基　　金：湖南创新型省份建设专项经费(2019GK1010)。

摘　　要：文章对长沙市中密砂砾-粉质黏土地层中某基坑开挖进行了现场地表沉降和支护结构位移的实测分析,利用有限差分程序建立了考虑建筑结构-地基-支护体系相互作用的三维数值模型,结合考虑加卸载路径的土体塑性硬化本构关系较好地模拟了开挖诱发的地层变形。在通过现场实测数据验证了数值模型合理性的基础上,对桩锚支护深基坑开挖影响下的地层位移、围护结构变形以及近邻浅基础建筑结构变形内力等进行了系统分析。分析结果表明:依托工程所采用的桩锚支护设计及施工方案能较好地控制地层变形并保障近邻既有建筑物的安全。锚索预应力的传递可导致地表出现隆起,基坑开挖引起的地表差异沉降会导致建筑物出现轻微偏转,引起基础下地基附加应力重分布,进而加剧差异沉降。基坑开挖后建筑结构柱附加弯矩趋向于集中在框架底层,建议类似工程中将安全监测重点可布置在紧临开挖侧的低楼层板柱连接处。对于基坑诱发变形的预测有必要考虑建筑物与地基的共同作用,忽视共同作用则有可能低估基坑开挖引起的建筑物差异沉降而造成潜在安全风险。A three-dimensional numerical model considering the interaction of building-ground-support system is established by the finite difference program,and the excavation-induced ground deformation can be simulated well by adopting the plastic hardening model of soil considering the loading and unloading stress path.The rationality of the numerical model was verified by field measurement data,and a systematic analysis was carried out on the ground displacement,the support deformation and the internal force and deformation of the existing building during the excavation.The analysis results show that the adopted pile-anchor support design and construction plan can control the ground deformation very well and ensure the safety of the existing building.The stress transfer of pre-tensioned anchor may lead to surface heave,and the differential settlement of ground surface caused by excavation may lead to slight deflection of the building and result in redistribution of stresses under the building foundation,which may further aggravate the differential settlement.After the excavation of the foundation pit,the additional bending moment of structure columns tends to be concentrated in the bottom floor of the building,the safety monitoring in similar projects should focus on the corresponding positions.Hence,to predict the deformations induced by deep excavation,it is necessary to consider interactions of building and ground,while ignoring the interactions may result in the underestimation on the potential safety risk caused by the differential settlement of the existing building due to the excavation.

关 键 词：基坑 变形特征 浅基础 差异沉降 既有建筑 

分 类 号：TU433[建筑科学—岩土工程]