半隧半路特殊隧道施工力学行为分析研究

Analysis and Research on the Mechanics Behavior in Construction of Special Part-tunnel and Part-roadbed Type Tunnel

研究目的:连拱隧道跨度大,在洞口边坡偏斜地段,为了避免高挖深填,保护自然环境,在埋深较大的一侧采用暗挖结构,埋深较浅的一侧修筑路基,中间是可以抵挡边坡推力同时兼作隧道边墙的耳墙,仍与中墙连成整体,即半隧半路的结构形式。半隧半路特殊隧道形式新颖,施工难度大,受力复杂,采用数值分析和现场测试开展了半隧半路特殊隧道施工力学行为研究。研究结论:暗洞开挖后,耳墙基础底部右侧围岩出现较大拉应力,形成弧形滑移带,实际施工中对耳墙基础底部采用锚杆+注浆进行加固。耳墙外侧在高8.5 m处出现较大拉应力,但小于混凝土抗拉设计值,经实测,耳墙水平位移值很小,表明耳墙的强度和稳定性都处于安全范围。暗洞的支护结构受力较小,施工完成后二衬应力变化较小,表明施工前对左侧边坡的加固处理作用明显,从而验证了半隧半路特殊隧道设计、施工的合理性,为以后类似工程提供借鉴。

Research purposes： As the span of continuous arch tunnel is big, in order to avoid the deep excavation and filling in the inclined area of the side slope at the tunnel opening and protect the natural environment, the subsurface excavation structure is adopted on the deep buried side, the subgrade is built on the shallow buried side, and the ear wall is built on the middle part, which can stand the pushing force of the side slope, be as the side wall of tunnel and connected with the middle wall. Such structural type is part- tunnel and part -roadbed type. The part -tunnel and part - roadbed type tunnel is fresh in style, difficult in construction and complicated in stressing, so it is necessary to do the research on the mechanics behavior in construction of this tunnel with numerical analysis and in - situ test. Research conclusions：After excavation of the blind tunnel, large tensile stress happened to the surrounding rock on the right side of the foundation bottom of the ear wall to form a are sliding zone. In construction, the foundation bottom of the ear wall was reinforced by anchor and grouting. Large tensile stress happened to the 8.5 m high area on the outside of the ear wall, but was smaller than the tensile design value of the concrete. The actual measurement showed the level displacement of the ear wall was small and the strength and stability of the ear wall were in the safe range. The stressing of the support structure for the blind tunnel was small and the stress of the secondary lining changed a little after completion of construction. All these showed the reinforcement of the side slope on left side before construction obtained good effect and verified the design and construction of this similar works.