富水断层带隧道变形力学机制及双梯度注浆NPR补偿对策

Mechanics of tunnel deformation in water-rich fault zone and double-gradient grouting NPR compensation countermeasures

云南他白依隧道位于青藏高原东麓,穿越多条断层构造带,其围岩软弱破碎,遇水强度骤降。原设计方案下围岩存在米级大变形,出现了拱架扭曲、仰拱隆起和突泥涌水等灾害。针对富水断层带隧道围岩破碎难题,首先通过矿物成分分析、点荷载试验及地应力测试,分析了富水断层带隧道变形力学机制及其转化,通过未注浆、常规注浆及双梯度注浆的围岩承载力试验,确定采用双梯度注浆工艺进行NPR锚索锚固;然后,通过数值模拟及现场试验,得出了最佳锚索数目;最后,通过现场应用,基于监测数据验证了双梯度注浆及高预紧力长短NPR锚索支护体系的可靠性。研究结果可为类似富水断层带隧道的大变形灾害控制提供参考。

Tabaiyi Tunnel is located in the eastern foothill of the Tibetan Plateau,crossing a multi-stage fault tectonic zone,and its surrounding rock is weak and broken,and its strength plummets when it en-counters water.The peripheral rock under the original design scheme has a large deformation of meter scale,and there are disasters such as twisted arch,elevated arch bulge and sudden mud and water surge.In order to solve the problem of peripheral rock fragmentation in the tunnel in the water-rich fault zone,firstly,the deformation mechanism of the tunnel in the water-rich fault zone and its transformation were analyzed through mineral composition analysis,point load test and ground stress test;through the bearing capacity test of the grouted peripheral rock with ungrouted,regular grouted and double-gradient grouted,it was determined to adopt the double-gradient grouted process for the anchoring of NPR anchor ropes;then,the optimal anchor rope number was derived from the numerical simulation and on-site test;finally,through the on-site application,the optimal anchor rope number was obtained.Finally,the relia-bility of the double gradient grouting and high preload long and short NPR anchor cable support system is verified through field application.Based on monitoring data,the results of the study can be used as a reference for the control of large deformation hazards in similar tunnels with water-rich fault zones.