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《建筑科学与工程学报》[ISSN:1673-2049/CN:61-1442/TU]

卷:

41卷

期数:

2024年02期

页码:

181-190

栏目:

岩土工程

出版日期:

2024-03-30

文章信息/Info

Title:

Influence laws of excavation sequence and early stiffness of inner support on stability of foundation pit in soft soil

文章编号:

1673-2049(2024)02-0181-10

作者:

管大刚^1,2,胡志明¹,郑鹏鹏¹,袁 山²,陈保国²,张艳林¹

(1. 中国水利水电第七工程局有限公司,四川 成都 610081; 2. 中国地质大学 工程学院,湖北 武汉 430074)

Author(s):

GUAN Dagang^1,2, HU Zhiming¹, ZHENG Pengpeng¹, YUAN Shan², CHEN Baoguo², ZHANG Yanlin¹

(1. Sinohydro Bureau 7 Co., Ltd, Chengdu 610081, Sichuan, China; 2. Faculty of Engineering, China University of Geosciences, Wuhan 430074, Hubei, China)

关键词:

深基坑;  软土;  开挖顺序;  混凝土内支撑;  早期刚度;  变形特性

Keywords:

deep foundation pit;  soft soil;  excavation sequence;  concrete inner support;  early stiffness;  deformation characteristic

分类号:

TU94

DOI:

10.19815/j.jace.2022.03084

文献标志码:

A

摘要:

深基坑开挖变形控制是软土基坑工程的难题,工程中常采用密集的混凝土内支撑来提高支撑刚度,然而实际工程中未能合理考虑软土深基坑的开挖顺序和混凝土内支撑早期刚度影响,往往导致基坑实际变形远大于设计值。结合珠三角水资源配置工程的软土深基坑,利用验证后的数值模拟方法研究了不同开挖顺序及混凝土内支撑早期刚度对基坑受力和变形特性的影响规律,得出了分层分区非对称开挖和对称开挖对地连墙水平位移和地表沉降的影响规律。结果表明:尽管非对称开挖会造成基坑两侧的地连墙位移和地表沉降差异,但是密集内支撑条件下非对称开挖比对称开挖对于基坑周围地表沉降和地连墙水平位移影响更小并能够大量节约工期; 受混凝土内支撑早期刚度影响,施作内支撑后越早进入下一步开挖,地连墙水平位移和周围地表沉降越大; 考虑内支撑早期刚度影响时基坑上部的内支撑轴力会增大,而下部的内支撑轴力会减小,早期刚度越小,这种趋势越明显; 现场施工时难以实时动态监测混凝土的弹性模量,极易造成内支撑轴力的早期监测数据失真,甚至给工程带来错误决策。

Abstract:

Deformation control of deep excavation is a difficult problem for deep foundation pit engineering in soft soil, and dense concrete inner supports are often used in engineering to improve support stiffness. However, the excavation sequence of deep foundation pit in soft soil and the early stiffness of concrete inner support are not reasonably considered in practice, which often cause the actual deformation of the foundation pit greater than the design value. According to the deep foundation pit in the Pearl River delta water resources allocation project, the verified numerical simulation method was used to study the influence laws of different excavation sequences and the early stiffness of concrete inner supports on the stress and deformation characteristics of soft soil foundation pit. The influence laws of asymmetric and/or symmetrical excavation on the diaphragm wall horizontal displacement and ground surface settlement were obtained. The results show that although asymmetric excavation will cause the displacement of diaphragm wall and surface settlement difference on both sides of foundation pit, asymmetric excavation can reduce time significantly compared with symmetrical excavation in the case of dense inner support. Moreover, due to the early stiffness of the concrete inner support, the earlier the next excavation is carried out after the applying inner support, the greater the diaphragm wall horizontal displacement and ground surface settlement will be. Considering the influence of the early stiffness of the inner support, the axial force of the inner support in the upper part of the foundation pit will increase, while the axial force of the inner support in the lower part will decrease, this trend will be more obvious at a lower early stiffness. Meanwhile, it is difficult to dynamically monitor the elastic modulus of concrete in real time during on-site construction, which is easy to cause the distortion of early monitoring data of inner support axial force, and even bring wrong decision-making to the project.

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备注/Memo

备注/Memo:

收稿日期:2023-03-21
基金项目:国家自然科学基金项目(52178370); 中国电建集团铁路建设有限公司科技项目(ZJSP-KY-001-YN)
作者简介:管大刚(1974-),男,高级工程师,E-mail:609358061@qq.com。
通信作者:陈保国(1981-),男,工学博士,副教授,E-mail:baoguo_chen@126.com。

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更新日期/Last Update: 2024-03-25