Abstract:

The causes and mechanical processes of water inrush and sand gushing of waterrich fault and fracture zone are analyzed so as to guarantee the safe construction of a mined metro tunnel in Huangdao District of Qingdao City. Under the action of excavation unloading and blasting disturbance, the thickness of waterproof layer of surrounding rock in waterrich fault and fracture zone with poor stability and without effective reinforcement exceeds limit, which leads to water inrush and sand gushing disaster. The comprehensive countermeasures of membrane bag grouting on ground surface and water stop grouting in tunnel are adopted considering disadvantages of mined metro tunnel construction, i. e. limited space and inconvenient material transport. The grouting effect shows that the working face after grouting is moist and with no flow water, the water leakage has been control within 1.5 L/(min·m); the seepage channels have been successfully sealed; and the safe and successful construction in water inrush and sand gushing sections of metro tunnel has been guaranteed.

Key words: mined metro tunnel, fault and fracture zone, water inrush and sand gushing, membrane bag grouting