富水复杂地质围岩稳定性评价与支护系统优化

研究目的:富水复杂地质隧道施工过程中,不良地质带受水-岩相互作用的影响,开挖过程中拱顶、拱腰等部位极易产生块体失稳,且隧底压力经常大于垂直地压,造成仰拱断裂、边墙下部内移错动甚至衬砌失稳破坏,从而给隧道施工造成很大的安全隐患,因此很有必要对围岩稳定性进行评价,并以此为基础对围岩支护系统进行优化探讨.研究结论:(1)隧道在弱风化的花岗岩中掘进时应尽快施作仰拱,使衬砌闭合成环；(2)CD法开挖段仰拱紧跟、衬砌尽早封闭成环很有必要；(3)文兴隧道与水库之间具有水力联系的可能性,对于隧道内的渗、涌水应及时采集水样进行必要的水化学及同位素分析,判断隧道内渗、涌水的来源.(4)隧道在断层破碎带的软弱围岩中掘进时,应尽早施做二次衬砌,必要时做专项的抗水压复合式衬砌设计；(5)一旦证实水库水与隧道之间存在水力连通,隧道的断层破碎带为力学和形变不良段,车行横洞应尽量避开该位置,适宜前移或后移数十米至微风化岩层段内.

Rock Stability Evaluation and Supporting System Optimization in WaterRich and Complex Stratum

Research purposes: During the tunnelling in water-rich and complex stratum,the bad geology was effected by the mutual effect of water and rock,the arch and arch side were easy to lose stability of block,and the impressure of bottom was bigger than that of vertical,which cause invert cracking,side wall displacement or even lining instability,so there were great security of hidden danger for tunnelling.It’s important support for rapid and safety tunnelling to do optimization discusses on rock supporting system which based on accurately evaluation of rock stability. Research conclusions:(1) The tunnel invert should be constructed to make the lining into closure condition as soon as possible during tunneling in the weak weathered granite rock section.(2) It is necessary for the CD method followed by invert excavation section and making the lining into a closure condition as early as possible.(3)Because of the possibility for the hydraulic connection between Wenxing tunnel and the reservoir,water samples should be collected in time to make a necessary chemistry and isotopic analysis to determine where the water seepage and gushing are from.(4) The secondary lining should be applied as soon as possible during tunneling in weak rock of the fracture zone.If necessary,a special anti water pressure composite lining design should be made.(5) Once the hydraulic connection between the tunnel and reservoir was confirmed and the deformation and mechanical condition of the tunnel in fault fracture zone was poor.The cross-hole for vehicle should be kept away from the weak point,it is suitable to change forward or backward 10 meters to the weak weathered granite section.