Dynamic responses and failure mechanisms of the existing tunnel under transient excavation unloading of an adjacent tunnel

查看全文 作　　者：Ying [1]Xu;Junxi [1]Tang;Yuchao [1]Yu;Wei [1]Yao;Bangbiao [1]Wu;Kaiwen [1,2]Xia 机构地区：[1]State Key Laboratory of Hydraulic Engineering Simulation and Safety,School of Civil Engineering,Tianjin University,Tianjin,300072,China;[2]Department of Civil and Mineral Engineering,University of Toronto,Toronto,Ontario,M5S 1A4,Canada 出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》索引2023年第15卷第11期,共13页 基　　金：supported by the National Natural Science Foundation of China(Grant Nos.42141010,51879184 and 12172253). 摘　　要：Engineering disasters(e.g.rock slabbing and rockburst)of the tunnel groups induced by the transient excavation of an adjacent tunnel threaten the stability of the existing tunnel,especially for those excavated by using the drill and blast tunneling(D&B).However,the dynamic response and failure mechanism of surrounding rocks of the existing tunnel caused by adjacent transient excavation are not clear due to the difficulty in conducting field tests and laboratory experiments.Therefore,a novel transient unloading experimental system for deep tunnel excavation was proposed in this study.The real stress path and the unloading rate can be reproduced by using this proposed system.The experiments were conducted for observing the dynamic response of the existing tunnel induced by adjacent transient excavation under different lateral pressure coefficients l(?0.4,0.6,0.8,1,1.2,1.4,1.6,1.8)with a polymethyl methacrylate(PMMA)specimen.The propagation of the impact wave and unloading surface wave was detected through the digital image correlation(DIC)analysis.The reflection of the unloading surface wave on the incident side of the existing tunnel(tunnel-E)was observed and analyzed.Moreover,the dynamic characteristics of the stress redistribution,the particle displacement and vibration velocity of surrounding rocks of tunnel-E were analyzed and summarized.In addition,the Mohr-Coulomb(MeC)failure criterion with tension cut-off was adopted to evaluate the stability of the existing tunnel under adjacent transient excavation.The results indicate that the incident side of the existing tunnel under the dynamic disturbance of transient excavation of an adjacent tunnel was more prone to fail,followed by the shadow side and the top/bottom side. 关 键 词：Tunnel groups Transient unloading Lateral pressure coefficient Stress redistribution Peak particle velocity(PPV)