高地应力条件下隧洞开挖诱发围岩振动特征研究

 采用理论分析、动力有限元数值模拟和振动监测数据对比等综合方法，研究高地应力条件下隧洞钻爆开挖诱发围岩振动的特征。发现高地应力条件下深埋隧洞钻爆开挖诱发的围岩振动由爆破振动和岩体初始地应力(开挖荷载)动态卸载诱发振动两部分叠加而成。在低岩体初始应力条件下，隧洞钻爆开挖过程围岩振动主要由爆炸荷载所引起；高地应力条件下，开挖荷载瞬态卸荷诱发振动的幅值可超过爆破振动而成为围岩振动的主要因素。利用四川省瀑布沟水电站引水隧洞进口段(地应力水平10 MPa)和尾水隧洞洞身段(地应力水平20 MPa)钻爆开挖过程的实测围岩振动资料，对理论分析和数值模拟结果进行验证。

STUDY ON VIBRATION CHARACTERISTICS OF SURROUNDING ROCK INDUCED BY TUNNEL EXCAVATION UNDER HIGH IN-SITU STRESS

The vibration characteristics of surrounding rock induced by the excavation of tunnel under high in-situ stress are studied with combined method of theoretical analysis，numerical simulation by dynamic finite element method(FEM) and verification with monitored field vibration data. It is found that the vibration induced by the excavation of tunnel under high in-situ stress is the result of superposition of blasting-induced vibration(BIV) and the transient unloading of in-situ stress induced vibration(DUIV). The study reveals that，under low in-situ stress condition，the vibration in surrounding rock is mostly induced by blasting load. Under high in-situ stress condition，the DUIV could become absolutely the main factor of total seismic wave induced by the excavation of tunnel with method of drilling and blasting. In the end，monitored vibration induced by the excavation of tail-water and inlet water tunnel in Pubugou Hydropower Station，Shichuan Province，China，is presented as a verification，which is corresponding to in-situ stresses of 10 and 20 MPa，respectively.