深埋隧洞TBM施工过程围岩损伤演化声发射试验

锦屏二级水电站深埋引水隧洞处于西南高应力区,地质条件复杂,岩爆、突水、塌方等工程地质灾害突出,掌握TBM开挖围岩损伤演化规律,设计有效的支护方案防治TBM施工过程地质灾害的发生是非常重要的。为此,开展TBM施工过程中声发射监测试验,研究TBM开挖过程中围岩损伤的演化规律。试验结果表明:沿洞轴线方向,TBM开挖时掌子面前约10m的范围内围岩已受到不同程度的损伤,TBM开挖后围岩损伤破裂主要集中在掌子面后7m的范围内,其中以掌子面后3m时为最;沿洞径方向,围岩受损伤的范围约9m,根据损伤程度的不同,划分为松动区、损伤区和扰动区,依次为距洞壁3,3～9和9～22m的范围。从力学的角度揭示损伤演化的机制和松动区、损伤区和扰动区划分的依据,为支护措施设计与支护时机的选取提供科学依据。分析讨论传感器选取、传感器布置、现场噪音及地质条件等各种因素对围岩损伤结果的影响及进一步发展和研究的方向。

ACOUSTIC EMISSION TEST ON DAMAGE EVOLUTION OF SURROUNDING ROCK IN DEEP-BURIED TUNNEL DURING TBM EXCAVATION

Diversion tunnels of Jinping II hydropower station，which is located at high stress zone，Southwest China，encounter many geological disasters，such as rockburst，water bursting，collapse of tunnel and so on during construction. It is very important to master damage evolution of surrounding rock and to design effective supporting measures to prevent or relieve geological disaster. Therefore，acoustic emission(AE) test was carried out and law of damage evolution of marble was studied. Different damage of surrounding rock comes up in 10 m range before free face during TBM working；and main damage or cracking is developed in 7 m range；3 m location is the most severe after free face. Damage range of surrounding rock is about 9 m in direction of tunnel axis. Relaxation，damage and disturbed zone are distinguished by evolution law of AE events，energy release and mechanism of damage evolution. Relaxation and damage range of surrounding rock are 3，3–9，and 9–22 m far from tunnel wall，respectively. Mechanism of damage evolution is illuminated by AE and mechanical characteristics before and after peak strength of rock mass. The influences of sensor types and arrangement，environmental noise and geological conditions on testing result are discussed；and the directions to improve testing result are also pointed out.