基于围岩虚拟支护力特性的隧道塌方机制及控制研究

为研究隧道塌方事故的典型模式及其演化规律，基于塌方案例统计分析结果，阐明隧道开挖面失稳塌方和关门塌方2类安全事故的基本特性，推导隧道围岩虚拟支护力纵向分布曲线，进一步从围岩应力释放角度揭示了虚拟支护力与2类塌方事故的关系，并给出了塌方事故的控制要求。研究表明： 1）开挖面失稳塌方和关门塌方2类由围岩和结构失稳引发的隧道塌方事故在事故次数（68%）、死亡人数（53.7%）和涉险人数（68%）方面占比较大，其中关门塌方事故单次事故涉险人数最多，潜在危害最大。2）隧道开挖面处的围岩虚拟支护力随着黏聚力的减小而降低，开挖面后方2倍半径处围岩的虚拟支护力已大部分释放（＜5%pi）。3）围岩变形和虚拟支护力释放的第2阶段内，围岩变形急剧，围岩虚拟支护力急剧释放且释放量较大，此阶段是隧道塌方控制的重点。

Tunnel Collapse Mechanism and Control Based on Virtual Support ForceCharacteristic of Surrounding Rock

Herein, based on the statistical analysis results of collapse cases, the basic characteristics of tunnel collapse accidents are revealed to investigate the typical model and evolution law of tunnel collapse accidents. Then, the longitudinal curve of the virtual support force is obtained, and the relationship between the virtual support force and collapse accidents is determined according to the release characteristics of the virtual support force. Finally, the control requirements of collapse accidents are given. The following results are found: (1)Collapse accidents caused by surrounding rock failure, including excavation face failure collapse and closed collapse, account for a significant number of accidents (68%), deaths (53.7%), and human in risk (68%); the closed collapse accident has the largest number of human in risk in a single accident with the greatest potential harm. (2) The virtual support force of surrounding rock at the tunnel face decreases with decreasing cohesion of surrounding rock; the virtual support force of surrounding rock at two times the radius behind excavation face is mostly released (less than 5%〖WT５《TNR#I》〗pi〖WT５《TNR》〗). (3) In the second stage of deformation and virtual support force release, the surrounding rock deforms sharply, and the virtual support force is also rapidly released with a large release amount. Therefore, the second stage is the key step in controlling the tunnel collapse.