(1 中冶成都勘察研究总院有限公司, 成都 610023; 2 西南交通大学土木工程学院, 成都 610031;3 四川能投节能环保投资有限公司, 成都 610023)

摘要: 以上海地区采用顺作法施工开挖深度为 20. 8m 的建筑基坑为研究对象,对五个施工阶段的地下连续墙侧向和竖向位移,立柱竖向位移和混凝土支撑轴力进行监测,以围护结构的侧向变形随深度、位置和施工阶段的差异分析基坑变形呈现的空间效应与深度效应,以立柱和地下连续墙的竖向变形规律分析基坑回弹特征,以混凝土轴力随时间变化规律分析支撑在各施工阶段的关键作用. 分析结果表明:地下连续墙在远离坑角位置比靠近坑角位置侧向位移更大,最大侧移范围为开挖深度的 0. 12% ~ 0. 41%,其侧向位移沿深度呈现“肚胀”形曲线,最大侧向位移发生在开挖深度以上 4m 到以下 2m 范围内;地下连续墙和立柱竖向位移主要以隆起为主,地下连续墙最大隆起位移为 9. 14mm,立柱最大隆起位移为地下连续墙的 4 倍;混凝土支撑对于下一阶段开挖起着关键作用,但对更深处土层开挖影响较小,混凝土支撑轴力最大值与地下连续墙的侧向位移密切相关.

关键词: 基坑开挖; 地下连续墙; 立柱; 侧向变形; 隆起和沉降; 施工监测; 空间效应; 深度效应

中图分类号:TU753 文献标志码:A 文章编号:1002⁃848X(2022)16⁃0116⁃09

DOI: 10. 19701 / j. jzjg. LS210165

Displacement and stress analysis of a Shanghai foundation pit at excavation stages

REN Dongxing1, HUANG Hai1, SHAO Kang2, LIU Huanhuan3, LUO Donglin1, XUE Peng1

(1 Chengdu Surveying Geotechnical Research Institute Co. , Ltd. of MCC, Chengdu 610023, China;2 School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China; 3 Sichuan EnergySaving and Environmental Protection Investment Co. , Ltd. , Chengdu 610023, China)

Abstract: Taking a foundation pit with the construction excavation depth of 20. 8m in Shanghai as the research object, thelateral and vertical displacement of the underground diaphragm wall, the vertical displacement of the stand column and theaxial force of the concrete support in the five construction stages were monitored. The spatial effect and depth effect of thefoundation pit deformation were analyzed by the lateral deformation of the enclosure structure with the difference of depth,location and construction stage, and the springing back characteristics of the foundation pit were analyzed by the verticaldeformation law of the stand column and the underground diaphragm wall. The key role of support in each construction stagewas analyzed based on the law of force variation with time. The analysis results show that the lateral displacement of theunderground diaphragm wall is larger at the position far from the pit corner than near the pit corner, and the maximumlateral displacement range is 0. 12% ~ 0. 41% of the excavation depth; its lateral displacement presents a bulging curvealong the depth, and the maximum lateral displacement occurs in the range of 4m above the excavation depth to 2m below;the vertical displacement of the underground diaphragm wall and stand column is mainly uplift, the maximum upliftdisplacement of the underground diaphragm wall is 9. 14mm, and the maximum uplift displacement of the stand column is 4times that of the underground diaphragm wall; concrete support plays a key role in the next stage of excavation, but haslittle effect on the excavation of deeper soil layers, and the maximum axial force of concrete support is closely related to thelateral displacement of the underground diaphragm wall.

Keywords: foundation pit excavation; underground diaphragm wall; stand column; lateral deformation; uplift andsettlement; construction monitoring; spatial effect; depth effect

∗国家自然科学基金(51808458).

第一作者:任东兴,硕士,高级工程师,主要从事岩土工程勘察设计、施工及研究工作,Email: rendx07@ 126. com.

[引用本文] 任东兴,黄海,邵康,等. 上海地区某基坑开挖阶段的位移与受力分析[ J]. 建筑结构,2022,52(16):116⁃124. REN Dongxing,HUANG Hai,SHAO Kang,et al. Displacement and stress analysis of a Shanghai foundation pit atexcavation stages[J]. Building Structure,2022,52(16):116⁃124.