Investigation on foundation pit uplift mechanism and tunnel response induced by deep excavation under complex support system: A case study

IF 8.3 1区工程技术 Q1 ENGINEERING, CIVIL

Underground Space Pub Date : 2025-07-01 DOI:10.1016/j.undsp.2025.03.002

Zhiguo Zhang , Jian Wei , Junjie Li , Linlong Mu , Wei Wo , Yin Ni

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引用次数: 0

Abstract

Pit excavation work often occurs directly above metro tunnels, causing adverse effects on the underlying existing operational shield tunnel. Current simplified solutions mainly adopt stress release method to reflect excavation of foundation pit, which is inappropriate for large soil uplift. A two-stage analysis based on modified Sagaseta solution with displacement-controlled boundary condition and tunnel-soil coordinated constrain is promoted for estimating the mechanical behavior of tunnel with joints. Specifically, the modified Sagaseta solution including gravity effects is firstly used to obtain the soil greenfield displacement caused by foundation pit excavation. Secondly, the Pasternak foundation model, incorporating tunnel-soil ellipse-shaped deformation, combines a variable stiffness Timoshenko beam at tunnel joints and ultimately obtains the tunnel displacement curve. Furthermore, a three-dimensional numerical simulation is also conducted for Jinqiao metro superstructure excavation project that involves a foundation pit situated directly above an existing metro tunnel. The feasibility of simplified solutions is verified with numerical simulation solutions and an engineering case. For investigating the key parameters, the parametric analyses are conducted, indicating that the greenfield displacement is highly related to modified uneven convergence Sagaseta solution. The ignoration of excavation width will overestimate the tunnel displacement as plane strain condition. Both equivalent bending and shear stiffness can only influence corresponding bending and shear tunnel deformation.

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复杂支护体系下深基坑开挖引起的基坑隆起机理及隧道响应研究——以实例为例

基坑开挖工程经常在地铁隧道的正上方进行，对地铁隧道的下卧既有施工盾构隧道造成不利影响。目前的简化解主要采用应力释放法来反映基坑开挖，不适用于较大的土体隆升。提出了一种基于变形控制边界条件和隧道-土协调约束的修正Sagaseta解的两阶段分析方法，用于估算含节理隧道的力学性能。具体而言，首先采用考虑重力效应的修正Sagaseta解求解基坑开挖引起的土体绿地位移。其次，考虑隧道-土体椭圆变形的帕斯捷尔纳克地基模型，在隧道节点处结合变刚度Timoshenko梁，最终得到隧道位移曲线；此外，还对金桥地铁上部结构开挖工程进行了三维数值模拟，该工程涉及地铁既有隧道正上方的基坑。通过数值模拟解和工程实例验证了简化解的可行性。为研究关键参数，进行了参数分析，表明绿地位移与修正的不均匀收敛Sagaseta解高度相关。忽略开挖宽度将高估作为平面应变条件的隧道位移。等效弯剪刚度只能影响相应的弯剪隧道变形。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Underground Space ENGINEERING, CIVIL-

CiteScore

10.20

自引率

14.10%

发文量

审稿时长

63 days

期刊介绍： Underground Space is an open access international journal without article processing charges (APC) committed to serving as a scientific forum for researchers and practitioners in the field of underground engineering. The journal welcomes manuscripts that deal with original theories, methods, technologies, and important applications throughout the life-cycle of underground projects, including planning, design, operation and maintenance, disaster prevention, and demolition. The journal is particularly interested in manuscripts related to the latest development of smart underground engineering from the perspectives of resilience, resources saving, environmental friendliness, humanity, and artificial intelligence. The manuscripts are expected to have significant innovation and potential impact in the field of underground engineering, and should have clear association with or application in underground projects.