Excavation unloading of foundation pit will lead to additional stress in adjacent subway tunnels. Excessive additional stress will cause instability of subway tunnel, and then affect the safety of subway operation. In order to study the influence law of additional stress on tunnels, the calculation formula of tunnel additional stress caused by foundation pit excavation is derived by using Mindlin theoretical solution and is verified based on the excavation project of a foundation pit group near a subway tunnel in Hangzhou. Then, the influence of three factors, including tunnel depth, horizontal distance between tunnel and foundation pit, and angle between tunnel and foundation pit, on additional stress in tunnel is analyzed. The research results show that: (1) with the increase of tunnel depth, the vertical additional stress of tunnel increase while the horizontal additional stress decrease, and the vertical and horizontal additional stress will decrease with the increase of the horizontal distance between tunnel axis and foundation pit; (2) during excavation of foundation pits, with the increase of horizontal distance between tunnel and foundation pit, the influence coefficient of tunnel depth on vertical additional stress decreases gradually, while the influence coefficient of tunnel depth on horizontal additional stress decreases first and then increases; (3) the vertical and horizontal additional stresses increase with the increase of the angle between tunnel axis and foundation axis, and the additional stress of the tunnel is mainly caused by excavation of the foundation pit which is the closest; (4) with the increase of the distance between tunnel axis and foundation pit axis, the reduction rate of vertical additional stress caused by pit group excavation is smaller than that caused by single pit excavation, while the reduction rate of horizontal additional stress caused by pit group excavation is larger than that caused by single pit excavation.
[1]杭州市地铁集团有限责任公司. 杭州市地铁集团有限责任公司轨道交通保护区管理实施办法[R]. 杭州:杭州市地铁集团有限责任公司,2016.(Hangzhou Metro Group Co., Ltd. Implementation Measures for the Management of Rail Transit Protected Areas of Hangzhou Metro Group Co., Ltd. [R]. Hangzhou: Hangzhou Metro Group Co., Ltd. 2016. (in Chinese))
[2]上海市市政工程管理局. 上海市地铁沿线建筑施工保护地铁技术管理暂行规定[R]. 上海:上海市市政工程管理局, 1994. (Shanghai Municipal Engineering Administration Bureau. Shanghai Interim Regulations on Metro Technical Management of Construction Protection along the Metro [R]. Shanghai: Shanghai Municipal Engineering Administration Bureau, 1994 (in Chinese))
[3]王利军, 邱俊筠, 何忠明, 等. 超大深基坑开挖对邻近地铁隧道变形影响[J]. 长安大学学报(自然科学版), 2020,40(6):77-85.(Wang Lijun, Qiu Junjun, He Zhongming, et al. Influence of excavation of super deep foundation pit on deformation of adjacent metro tunnel[J]. Journal of Chang' an University (Natural Science Edition), 2020,40(6):77-85. (in Chinese))
[4]伍尚勇, 杨小平, 刘庭金. 双侧深基坑施工对紧邻地铁隧道变形影响的分析[J]. 岩石力学与工程学报, 2012,31(增1):3452-3458.(Wu Shangyong, Yang Xiaoping, Liu Tingjin. Analysis of influence on deformation of adjacent subway tunnel due to bilateral deep excavations [J]. Chinese Journal of Rock Mechanics and Engineering,2012,31(Supp.1):3452-3458. (in Chinese))
[5]左殿军, 史林, 李铭铭, 等. 深基坑开挖对邻近地铁隧道影响数值计算分析[J]. 岩土工程学报, 2014,36(增2):391-395.(Zuo Dianjun, Shi Lin, Li Mingming, et al. Numerical analysis of influence of deep excavations on adjacent subway tunnels[J]. Chinese Journal of Geotechnical Engineering,2014,36(Supp.):391-395. (in Chinese))
[6]Ye S, Zhao Z, Wang D. Deformation analysis and safety assessment of existing metro tunnels affected by excavation of a foundation pit[J]. Underground Space, 2020,6(4):421-431.
[7]Yang T, Tong L, Pan H, et al. Effect of excavation sequence on uplift deformation of underlying existing metro tunnel[J]. Journal of Performance of Constructed Facilities, 2021,35(2):4021003.
[8]李振兰. 基坑开挖引起紧邻既有地铁隧道变形的规律研究[D].西安:西安建筑科技大学,2022.(Li Zhenlan. Study on the law of deformation of adjacent to existing subway tunnel caused by excavation of foundation pit[D].Xi'an:Xi'an University of Architecture and Technology,2022.(in Chinese))
[9]刘鑫菊,郑刚,周海祚,等.临近基坑开挖引起的隧道变形预测分析[J].重庆大学学报,2022,45(7):37-44.(Liu Xinju, Zheng Gang, Zhou Haizuo et al. Prediction analysis of tunnel deformation caused by adjacent foundation pit excavation[J].Journal of Chongqing University,2022,45(7):37-44.(in Chinese))
[10]胡欣. 模型试验模拟不同工况下基坑开挖对既有隧道的影响[J]. 路基工程, 2015(6):5.(Hu Xin. Influence of foundation pit excavation under different conditions simulating by model test on existing tunnel[J]. Subgrade Engineering,2015(6):151-155. (in Chinese))
[11]Qasem Al-Madhagi Ashraf Abdulraqeb Abdo. 干砂地层基坑开挖对旁侧隧道影响离心模型试验研究[D]. 浙江:浙江大学, 2018.(Qasem Al-Madhagi Ashraf Abdulraqeb Abdo. Centrifuge Tests on Effects of Excavation on Nearby Existing Tunnel in Sandy Soil[D]. Zhejiang: Zhejiang University, 2018. (in Chinese))
[12]魏少伟. 基坑开挖对坑底已建隧道影响的数值与离心试验研究[D]. 天津:天津大学, 2010.(Wei Shaowei. Centrifuge and numerical studies of the influence of basement excavation on the underlying tunnel [D]. Tianjin: Tianjin University, 2010. (in Chinese))
[13]Huang H, Huang X, Zhang D. Centrifuge modelling of deep excavation over existing tunnels[J]. Geotechnical Engineering, 2015,167(1):3-18.
[14]Ng C, Shi J, Hong Y. Three-dimensional centrifuge modelling of basement excavation effects on an existing tunnel in dry sand[J]. Canadian Geotechnical Journal, 2013,50(8):874-888.
[15]闫旭丽,姚爱军,周一君,等.基坑施工邻域隧道围土应力路径演变规律研究[J].地下空间与工程学报,2019,15(5):1528-1540.(Yan Xuli, Yao Aijun, Zhou Yijun, et al. Study on the evolution law of stress path of tunnel cranking in the neighborhood of foundation pit construction[J].Chinese Journal of Underground Space and Engineering,2019,15(5):1528-1540. (in Chinese))
[16]魏纲, 赵城丽. 基坑开挖引起临近地铁隧道的附加荷载计算方法[J]. 岩石力学与工程学报, 2016,35(增1):3408-3417.(Wei Gang,Zhao Chengli. Calculation method of additional load of adjacent metro tunnels due to foundation pit excavation[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(Supp.1):3408-3417. (in Chinese))
[17]张治国, 蒋康明, 王志伟, 等. 考虑Pasternak地基模型的基坑开挖诱发既有隧道纵向变形理论分析[J]. 隧道建设(中英文), 2020,40(增1):57-67.(Zhang Zhiguo, Jiang Kangming, Wang Zhiwei, et al.Theoretical analysis on longitudinal deformation of existing tunnel induced by adjacent foundation pit excavation considering Pasternak foundation model [J]. Tunnel Construction,2020,40(Supp.1):57-67. (in Chinese))
[18]宗翔. 基坑开挖卸载引起下卧已建隧道的纵向变形研究[J]. 岩土力学, 2016(增2):571-577.(ZONG Xiang. Study of longitudinal deformation of existing tunnel due to above excavation unloading[J]. Rock and Soil Mechanics, 2016(Supp.2):571-577. (in Chinese))
[19]康成, 叶超, 梁荣柱, 等. 基坑开挖诱发下卧盾构隧道纵向非线性变形研究[J]. 岩石力学与工程学报, 2020,39(11):2341-2350.(Kang Cheng, Ye Chao, Liang Rongzhu, et al. Nonlinear longitudinal deformation of underlying shield tunnels induced by foundation excavation[J]. Chinese Journal of Rock Mechanics and Engineering,2020,39(11):2341-2350. (in Chinese))
[20]冯国辉,徐长节,郑茗旺,等.考虑剪切变形下基坑开挖引起下卧既有隧道的纵向变形研究[J].铁道学报,2022,44(3):132-141.(Feng Guohui, Xu Changjie, Zheng Mingwang, et al. Study on longitudinal deformation of existing tunnel under the excavation of foundation pit considering shear deformation[J].Journal of the China Railway Society,2022,44(3):132-141. (in Chinese))
[21]冯国辉,陈光仔,张迪,等.基坑开挖诱发下卧既有隧道隆起变形解析解[J].铁道科学与工程学报,2023, 20(10):3908-3917.(Feng Guohui, Chen Guangzai, Zhang Di, et al. Analytical solution of uplift deformation of existing tunnel induced by excavation of foundation pit[J].Journal of Railway Scienceand Engineering,2023, 20(10):3908-391.(in Chinese))
[22]周泽林, 陈寿根, 陈亮, 等. 基坑施工对下卧地铁隧道上抬变形影响的简化理论分析[J]. 岩土工程学报, 2015,37(12):2224-2234.(Zhou Zelin, Chen Shougen, Chen Liang, et al. Analysis of uplift deflection of subway tunnel due to adjacent pit excavation[J]. Chinese Journal of Geotechnical Engineering, 2015, 37(12): 2224-2234. (in Chinese))
[23]周泽林, 陈寿根, 张海生, 等. 明挖卸荷对下卧地铁双洞隧道变形影响的计算方法研究[J]. 铁道学报, 2016,38(9):109-117.(Zhou Zelin, Chen Shougen, Zhang Haisheng, et al. Calculation method study of deformation effect of underlying double-hole subway tunnels in open cutting unloading case[J]. Journal of the China Railway Society, 2016, 38(9) : 109-117. (in Chinese))
[24]Hideaki T. Formulas for an infinitely long bernoulli-euler Beam on the Pasternak model[J]. Soils and Foundations, 2004,44(5):109-118.
