TBM有压输水隧洞内张钢圈-管片-围岩组合结构联合承载力学特性分析

Combined bearing mechanical characteristics of composite structure of inner tensioned steel ring-segment-surrounding rock in a TBM pressurized water conveyance tunnel

为探究全断面隧道岩石掘进机(tunnel boring machine,TBM)有压输水隧洞内张钢圈-管片-围岩组合结构的受荷状态,以榕江―关埠引水工程中Ⅴ类围岩TBM有压输水隧洞段为研究对象,建立内张钢圈-管片-围岩组合结构三维精细化有限元模型,研究内水压力、围岩类型对组合结构力学特性的影响。研究结果表明:采用内张钢圈加固隧洞结构能有效控制隧洞变形,减小管片拉应力及受拉区范围,提高组合结构的承载能力;内水压力作用下管片压应力、竖向变形、接缝张开度、连接螺栓应力、内张钢圈应力、锚杆应力均较无内水压力作用下有所减小,但管片拉应力和接缝错台分别增大了19.68%、39.25%,其主要原因为内水压力作用致使隧洞结构整体呈现向外膨胀,在充水运营期间应加强内水压力作用下的安全监测;在外部水土压力和内水压力共同作用下,围岩类型的改变使组合结构中连接螺栓应力、管片接缝错台、锚杆应力分别提高37.11%、15.29%、14.75%,其主要原因为围岩岩性越差承担荷载能力越弱,在围岩类型的过渡区域应进行重点监测;此外,在外部水土压力和内水压力共同作用下,组合结构中围岩、管片、内张钢圈、锚杆的荷载分担率分别为21.38%、43.08%、24.01%和11.53%,内张钢圈荷载分担率较无内水压力作用提高了34.06%,内水压力作用提高了内张钢圈分担荷载的效果;组合结构中围岩的分担率随围岩类型(Ⅲ类、Ⅳ类、Ⅴ类)的增加而减小,相同荷载下Ⅲ类围岩的荷载分担率较Ⅴ类围岩提高了16.96%。该研究成果可为类似隧洞工程的衬砌设计及后期加固措施提供理论参考。

In order to investigate the loading state of the combined structure of inner tension ring-segment-surrounding rock in tunnel boring machine(TBM)pressurized water conveyance tunnel,a three-dimensional refined finite element model of the composite structure comprising the inner tension ring-segment-surrounding rock in a TBM pressurized water conveyance tunnel has been established for the Class V TBM pressurized water conveyance tunnel of the Rongjiang-Guanbu water diversion project.The study has yielded important findings.The reinforcement of the tunnel structure with internal tensile steel ring can effectively control the deformation of the tunnel,reduce the tensile stress of the segment and the range of tension zone,and improve the bearing capacity of the composite structure.Under the action of internal water pressure,various parameters such as compression stress,vertical deformation,joint opening degree,stress of connecting bolts,stress of the inner tension ring,and stress of anchor rods all decrease compared to conditions without internal water pressure.However,the tensile stress of the segment and joint misalignment increase by 19.68%and 39.25%,respectively.The main reason is that the overall expansion of the tunnel structure is caused by internal water pressure.This underscores the need for strengthened safety monitoring during water filling operations.Under the combined action of external water and soil pressure and internal water pressure,the change of surrounding rock type lead to increased stress of connecting bolt,the misalignment of segment joints and the stress of anchor bolt by 37.11%,15.29%and 14.75%,respectively.This highlights the importance of monitoring in the transition area of surrounding rock types where the load-bearing capacity is poorer.In addition,under the combined action of external water and soil pressure and internal water pressure,the load sharing rate of surrounding rock,segment,inner tension steel ring and anchor bolt is 21.38%,43.08%,24.01%and 11.53%,respectively.The load sharing rate of inner tension steel ring is 34.06%higher than that without internal water pressure.The effect of internal water pressure improves the load sharing effect of the inner tension steel ring.The load sharing ratio of surrounding rock in composite structure decreases with the increase of surrounding rock types(ClassⅢ,ClassⅣ,ClassⅤ),and the load sharing ratio of classⅢsurrounding rock is 16.96%higher than that of ClassⅤunder the same load.These research findings provide valuable theoretical reference for lining design and late reinforcement measures of similar tunnel projects.