筒式基坑开挖变形特性及稳定性分析

李红军; 冷远; 张士龙; 刘昌永

doi:10.3973/j.issn.2096-4498.2022.08.008

隧道建设 >

2022 , Vol. 42 >Issue 8: 1395 - 1403

DOI: https://doi.org/10.3973/j.issn.2096-4498.2022.08.008

研究与探索

筒式基坑开挖变形特性及稳定性分析

李红军 ,
冷远 ,
张士龙 ,
刘昌永

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（1. 中交二航局第三工程有限公司, 江苏镇江〓212000; 2. 哈尔滨工业大学, 黑龙江哈尔滨〓150000）

李红军（1981—），男，吉林长春人，2003年毕业于长春工程学院，道路桥梁与渡河工程专业，本科，高级工程师，现从事路桥及市政工程研究工作。Email： stivenlijun@163.com。

网络出版日期: 2022-09-09

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Deformation Characteristics and Stability of ShaftType Foundation Pit Excavation

LI Hongjun ,
LENG Yuan ,
ZHANG Shilong ,
LIU Changyong

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(1. China Communications 2nd Navigational Bureau 3rd Engineering Co., Ltd., Zhenjiang 212000, Jiangsu, China;  2. Harbin Institute of Technology, Harbin 150000, Heilongjiang, China)

Online published: 2022-09-09

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摘要

为研究井筒式基坑开挖变形特性和坑中坑开挖对基坑整体稳定性的影响，以哈尔滨省委广场井筒式地下停车场为工程背景展开分析。首先，对井筒式基坑的变形监测方案及结果进行评述。然后，采用有限元软件MIDAS/GTS建立井筒式基坑的有限元计算模型，与监测结果对比验证计算模型的准确性；在此基础上，探讨井筒式基坑施工过程中的环向拱效应演变规律，并对基坑直径和围护桩桩径等影响因素进行参数化分析。最后，基于强度折减法对井筒式基坑坑内的二次开挖进行分析，研究内坑的平台宽度和深度对基坑稳定性的影响。结果表明： 1）现场实测的桩体水平位移最大为3.5 mm，最大沉降量为11.6 mm； 2）圆形基坑的环向拱效应可以采用土体的中主应力矢量图进行表达，随着基坑开挖深度的逐步增大，其环向拱效应作用的土体范围也逐步扩大； 3）当内外坑开挖深度比为0.44时，需考虑内坑开挖对基坑稳定性的影响。

关键词： 地下车库; 井筒式基坑; 围护结构; 拱效应; 二次开挖; 基坑监测; 有限元分析

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李红军 , 冷远 , 张士龙 , 刘昌永 . 筒式基坑开挖变形特性及稳定性分析[J]. 隧道建设, 2022 , 42(8) : 1395 -1403 . DOI: 10.3973/j.issn.2096-4498.2022.08.008

Abstract

A case study of the shafttype underground parking garage of Harbin Provincial Party Committee Square is conducted to examine the deformation characteristics of shafttype foundation pit excavation and the influence of pitinpit excavation on the overall stability of the foundation pit. First, the deformation monitoring scheme and results of the shafttype foundation pit are reviewed. Second, the finite element software MIDAS/GTS is used to create a finite element calculation model for shafttype foundation pit, and the accuracy of the calculation model is verified by comparing it with the monitoring results. On this basis, the evolution law of the annular arch effect in the construction process of shafttype foundation pit is discussed, and influencing factors such as foundation pit diameter and supporting pile diameter are analyzed. Finally, the secondary excavation in the shaft pit is analyzed using the strength reduction method, and the influence of the platform width and pit depth on the pit stability is studied. The results are as follows: (1) The maximum measured horizontal displacement of the pile is 3.5 mm, and the maximum settlement is 11.6 mm. (2) The circular arch effect of the circular foundation pit can be expressed using the soil′s medium principal stress vector diagram. The soil range of the circular arch effect gradually expands as the excavation depth of the foundation pit is gradually increased. (3) When the excavation depth ratio of the inner and outer pits is 0.44, the influence of inner pit excavation on foundation pit stability should be considered.

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