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鉴于高含水量土层中锚杆成孔困难、注浆效果差、自进式锚杆抗拉拔力低等缺点,提出在高含水量土质隧道中取消系统锚杆,初期支护采用“型钢拱架+喷射混凝土+钢筋网+锁脚锚管+纵向连接筋”组成的新型支护结构。为了评价这种新型支护结构的受力、变形特性,以天恒山隧道为工程依托,通过现场试验和有限元数值分析两种方法,对隧道拱部下沉、净空收敛、喷射混凝土应力、钢架应力进行了综合分析。监测及计算结果表明,支护结构的变形和受力均在允许范围之内;隧道施工过程中拱顶沉降与拱脚沉降大致相同,即拱部产生了整体下沉;上台阶开挖引起的变形比例较大,中台阶、仰拱开挖及封闭后引起变形比例较小;喷射混凝土拱部受力较大,其他部位受力较小;钢架应力分布不均匀,拱部应力大于边墙和仰拱应力。
In view of the difficulties of pore formation, poor grouting effect and low anti-pull force of self-propelled anchor in high water content soil, it is proposed that the system anchor be canceled in the high water content soil tunnel and the initial support should be “ Steel arch + spray concrete + steel mesh + anchor anchor pipe + longitudinal connection ribs ”consisting of a new type of support structure. In order to evaluate the stress and deformation characteristics of this new type of supporting structure, based on the Tianhengshan tunnel project, through field test and finite element numerical analysis, the effects of tunnel arch settlement, headroom convergence, shotcrete stress, Stress conducted a comprehensive analysis. The monitoring and calculation results show that the deformation and stress of the support structure are within the allowable range. The settlement of the vault during the construction of the tunnel is almost the same as that of the settlement of the arch foot, that is, the entire sinking of the arch has occurred. The deformation ratio is large, and the deformation ratio of the middle step and the inverted arch after excavation and closure is small; the stress of the sprayed concrete arch is larger and the stress of other parts is smaller; the stress distribution of the steel frame is not uniform and the stress of the arch is greater than that of the wall And inverted arch stress.