重叠隧道先挖扰动作用对后挖加固效用的影响
徐前卫1蒋承志1叶颜伟2余航飞1袁枫杰2覃早2张骏3
Disturbance Action of First Excavation on Reinforcement Effect of Later Excavation in layered Tunnels
XU Qianwei1JIANG Chengzhi1YE Yanwei2YU Hangfei1YUAN Fengjie2QIN Zao2ZHANGJun3
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作者信息:1.同济大学道路与交通工程教育部重点实验室，201804，上海
2.中铁二局第五工程有限公司，610091，成都
3.沪宁城际铁路股份有限公司，210024，南京
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Affiliation:1.Key Laboratory of Road and Traffic Engineering of Ministry of Education, Tongji University, 201804, Shanghai， China
2.China Railway Erju No.5 Engineering Co., Ltd., 610091, Chengdu， China
3.Shanghai-Nanjing intercity railway Co., Ltd., 210024, Nanjing， China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.2024.06.041
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中图分类号/CLCN:TU433
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栏目/Col:研究报告
摘要:
［目的］在超近距离上下重叠隧道工程中，先挖隧道会导致围岩发生难以预测的损伤，进而影响后挖隧道的顺利施工，增大工程建设难度。因而有必要研究重叠隧道施工过程中先挖隧道对后挖隧道的影响效应。［方法］依托重庆市某隧道工程，采取数值模拟的方法比较分析了先挖的下层隧道开挖引起的围岩的应力分布规律及变形特征，并根据上层隧道在不同工况下的受力特征和变形规律，分析了锚杆加固措施的变形控制效果与下层隧道开挖产生的围岩弱化效应之间的关系。［结果及结论］下层先挖隧道施工引起拱顶区域沉降，最大沉降量为4.1 mm；拱底区域隆起，最大隆起量为6.9 mm；根据围岩应力分布变化程度及等效塑性应变范围，下层隧道围岩的松动区域等效为圆形范围，且松动圈平均厚度为2.5 m；上层隧道的开挖卸荷会引发下层隧道上浮；对下层隧道松动圈围岩采取锚杆加固措施后，对应围岩的强度折减系数为0.70~0.75。
Abstracts:
［Objective］ In the ultra-close layered tunnel construction, the preceding excavated tunnel can cause unpredictable damage to the surrounding rock, which will affect the smooth construction of the following tunnel and increase the difficulties of engineering construction. Therefore, it is necessary to study the effect of the preceding tunnel on the following ones in the layered tunnel construction. ［Method］ Based on a tunnel project in Chongqing, a numerical simulation method is used to compare and analyze the stress distribution patterns and deformation characteristics of the surrounding rock caused by the preceding excavation of the lower layer tunnel. According to the stress characteristics and the deformation law of the upper layer tunnel under different working conditions, the relationship between the deformation control effect of the anchor rod reinforcement measures and the weakening effect of the surrounding rock caused by the lower layer tunnel excavation is analyzed. ［Result & Conclusion］ The preceding excavation of the lower layer tunnel causes the vault area settlement with a maximum of 4.1mm and the arch bottom area bulging with a maximum of 6.9 mm. According to the variation intensity of the stress distribution and the equivalent plastic strain range of the surrounding rock, the loosening area of the lower layer tunnel surrounding rock is equivalent to a circular range, and the average thickness of the loosening circle is 2.5m.The excavation unloading of the upper layer tunnel will cause the lower layer tunnel up floating. After the anchor rod reinforcement measures are taken for the surrounding rock in the lower layer tunnel loosening circle, the strength coefficient of the corresponding surrounding rock is reduced to 0.70 ~ 0.75.
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