Long-term performance of metro tunnels induced by adjacent large deep excavation and protective measures in Nanjing silty clay
Long-term performance of metro tunnels induced by adjacent large deep excavation and protective measures in Nanjing silty clay
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DOI：
10.1016/j.tust.2019.103147
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发表时间：
2020-01-01
影响因子：
6.9
通讯作者：
Zhang, Qian-Bing
中科院分区：
文献类型：
--
作者：
Liu, Bo;Zhang, Ding-Wen;Zhang, Qian-Bing
本文介绍了在南京粉质粘土中，在两条正在运行的地铁隧道附近进行大型地下室开挖的施工。为了研究开挖对既有隧道的影响，对隧道施工前可能发生的变形进行了数值模拟。然后，根据得到的数值结果，提出了有针对性的监测方案，并进行了为期4年的深基坑开挖及隧道响应的综合现场监测。监测项目包括连续墙横向位移、隧道顶沉降、弹簧线水平位移、管片缝直径收敛和开口宽度。根据监测结果，分析了隧道变形演变规律，并对隧道结构的安全性进行了评价。根据评价结果，提出并采用微扰动注浆对变形隧道进行修正，并对处理效果进行了评价。结果表明：隧道顶冠沉降、弹簧线水平位移和直径收敛的演化可分为缓慢增长阶段、快速增长阶段和稳定增长阶段，分别对应深基坑开挖前、主开挖阶段和开挖后阶段；基于简支梁原理，隧道沉降范围取最大沉降监测断面与沉降为0断面之间距离的2倍。在微扰动注浆处理过程中，变形隧道分别经历了修正阶段和回弹阶段，微扰动注浆很好地修正了相邻开挖引起的附加变形。
This paper presents the construction of a large-scale basement excavation adjacent to the two running metro tunnels in Nanjing silty clay. To investigate the influences of excavation on existing tunnels, a numerical modelling was carried out to predict the possible deformation of tunnels before construction. Then, referring to the obtained numerical results, a targeted monitoring program was proposed and comprehensive field monitoring was performed to monitor the deep excavation and tunnels response over four years. The monitoring items include the diaphragm wall lateral deflection, the tunnel crown settlement, the springline horizontal displacement, the diameter convergence and the opening width of the segment joint. Based on monitoring results, the evolution of tunnels deformation was analysed, and the safety of tunnel structures was evaluated. According to the evaluation results, micro-disturbance grouting was proposed and adopted to correct the deformed tunnel, and the treatment effectiveness was evaluated. The results indicate that the evolution of tunnel crown settlement, springline horizontal displacement and diameter convergence can be divided into slow growth, rapid growth and stable growth stages, and they correspond to the pre-excavation, main excavation and post-excavation stages of deep excavation respectively. Based on the simple beam principle, the settlement range of tunnel can be taken two times the distance between the monitoring section with the maximum settlement and the section with the settlement of 0. In the process of micro-disturbance grouting treatment, the deformed tunnel goes through a correction stage and a rebound stage respectively, and the additional deformation induced by adjacent excavation is well corrected by micro-disturbance grouting.