某过断层深埋高水头TBM输水隧洞围岩-支护结构响应规律

Response Law of a Deep-buried TBM Water Conveyance Tunnel with High External Water Pressure Passing Through Faults

为了研究过断层深埋高水头敞开式TBM输水隧洞支护结构的响应规律,对不同支护方案下某过断层深埋高水头敞开式TBM隧洞围岩与支护结构的响应规律进行对比分析,选出最合适的支护设计方案。建立TBM隧洞动态开挖-支护精细仿真模型,逐个研究动态开挖-支护中围岩、锚杆、钢拱架、初喷混凝土、二衬的响应规律。结果表明:依次支护管棚、锚杆、钢拱架、固结灌浆、衬砌后,围岩拱顶变形分别降为不支护时的59.4%、32.9%、32.9%、4.1%、3.2%。盾尾离开后各响应突增,增幅逐步减缓且最终趋于稳定,衬砌支护后突降并稳定。锚杆应力分布不均,支护后拱腰处锚杆应力比拱顶增加快,各锚杆应力越靠近洞壁处越大。管棚+锚杆+钢拱架+固结灌浆+初喷+二衬可保证安全,但需固结围岩弹性模量、黏聚力及内摩擦角分别提高1.0、1.0、0.21倍。

The design of the support structure for TBM water conveyance tunnels, which are characterized by penetrating faults, being deeply buried, and having high external water pressure, often lacks detailed analysis. The response of each support structure is still unclear. Therefore, this work analyzed the response laws of surrounding rock and support structure during the excavation-support process of this type of TBM tunnel under different support schemes. Firstly, A three-dimensional fine simulation model of dynamic excavation-supporting of TBM tunnels in line with practical construction methods was established. Secondly, the response laws of surrounding rock, anchor rod, steel arche, initial sprayed concrete, and secondary lining in dynamic excavation-support were gradually analyzed after the dismantling of the support scheme. The results indicate that all supporting structures can effectively reduce the deformation of surrounding rock. The deformation of the surrounding rock before lining support, as well as the stress response of anchor rod and steel arche, all increase with excavation, and the amplitude gradually decreases and eventually tends to stabilize. After support, each response immediately decreases and stabilizes. The stress distribution of anchor rod is uneven. The stress of anchor rod near the arch waist increases faster than that of anchor rod at the arch crown after support, and the stress of each anchor rod near the inner wall of the tunnel is greater than that far away from the inner wall of the tunnel. The support plan, consisting of a pipe shed, anchor rod, steel arche, consolidation grouting, initial spraying, and secondary lining, can ensure engineering safety. However, it is necessary to increase the elastic modulus, cohesive force, and internal friction angle of the consolidated surrounding rock by 1.0, 1.0, and 0.21 times, respectively.