Mu Zhiyuan, Wei Gang, Zhang Zhiguo, Jiang Haibo, Xu Tianbao, Qi Yongjie
Department of Civil Engineering, Hangzhou City University, Hangzhou, 310015, China.
Key Laboratory of Safe Construction and Intelligent Maintenance for Urban Shield Tunnels of Zhejiang Province, Hangzhou, 310015, China.
Sci Rep. 2024 Oct 5;14(1):23167. doi: 10.1038/s41598-024-72731-2.
This study aims to investigate the responses of shield tunnel structures subjected to disturbances caused by bilateral pit excavation, and it systematically reveals for the first time the impact mechanism of bilateral pit excavation on the distribution of perimeter pressure and deformation patterns of shield tunnels. Using a bilateral pit excavation project in Nanjing as a case study, this research establishes methods for calculating longitudinal displacement and circumferential pressure of tunnels under bilateral pit excavation conditions, employing the image source method for analysis. A refined three-ring segment model is developed, and the load structure method is used to analyze the impact of deep foundation excavation on the tunnel located between the two excavation sites. The results indicate that, compared to unilateral excavation, bilateral excavation significantly increases the perimeter pressure at the top and bottom of the tunnel, with a smaller increase in pressure at the arch waist. The deformation pattern is characterized by contraction at the top and bottom and expansion at the waist, forming a transverse elliptical deformation. The maximum vertical convergence values of the middle segment ring are 25.00 mm at the top and 25.88 mm at the bottom, with a vertical absolute convergence value of 44.5 mm and a convergence ratio (ΔD/D) of 0.72%. As the foundation coefficient increases, the perimeter pressure at the top and bottom of the tunnel also increases. When the tunnel is closer to the foundation pits (S decreases), the perimeter pressure at the bottom of the tunnel increases. Conversely, as the distance between the two foundation pits (S) increases, the impact of excavation on the tunnel shifts from the upper part to the lower part, resulting in decreased upper perimeter pressure and increased lower perimeter pressure. The research findings provide important references for similar engineering projects.
本研究旨在探讨盾构隧道结构在双侧基坑开挖引起的扰动作用下的响应情况，并首次系统揭示双侧基坑开挖对盾构隧道周边压力分布及变形模式的影响机制。以南京某双侧基坑开挖工程为例，本研究建立了双侧基坑开挖条件下隧道纵向位移和环向压力的计算方法，采用镜像源法进行分析。建立了精细化三环管片模型，运用荷载结构法分析深基坑开挖对位于两个开挖部位之间隧道的影响。结果表明，与单侧开挖相比，双侧开挖显著增加了隧道顶部和底部的周边压力，拱腰处压力增加较小。变形模式表现为顶部和底部收缩、腰部扩张，形成横向椭圆变形。中间管片环的最大竖向收敛值顶部为25.00mm，底部为25.88mm，竖向绝对收敛值为44.5mm，收敛率（ΔD/D）为0.72%。随着地基系数的增大，隧道顶部和底部的周边压力也增大。当隧道离基坑较近时（S减小），隧道底部的周边压力增大。反之，随着两个基坑之间的距离（S）增大，开挖对隧道的影响从上部转移到下部，导致上部周边压力减小，下部周边压力增大。研究结果为类似工程项目提供了重要参考。
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