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隧道的衬砌对于隧道稳定性和施工安全具有很大的影响。首先总结了隧道的常见破坏形式和常用计算理论及方法,选择离散元UDEC方法,以某公路隧道为研究对象,设计了未采取初期衬砌,以及初期衬砌接触面黏聚力为0、0.01、0.03、0.05、0.08、0.10、0.12、0.15 MPa,内摩擦角为0°、5°、10°、15°、20°、25°、30°、35°、40°、45°,抗拉强度为0、0.001、0.005、0.010、0.015、0.020、0.025、0.030、0.035MPa等计算工况。经不同工况塑性区和不平衡力计算结果的对比分析发现:不采取初期衬砌,隧道的破坏形式主要是洞顶掉块;采取初期衬砌,接触面黏聚力的临界值为0.08MPa,内摩擦角的临界值为20°,抗拉强度的临界值为0.03MPa。如果强度低于这些值,则隧道的塑性区扩大,不平衡力较大,表明隧道不稳定。这些可以作为设计参考值。
Tunnel lining has great influence on tunnel stability and construction safety. First of all, the common failure forms and common calculation theories and methods of tunnels are summarized. The discrete element UDEC method is selected. Taking a highway tunnel as the research object, the initial lining is not adopted and the cohesive force of the initial lining contact surface is 0, 0.01, 0.03 , 0.05,0.08,0.10,0.12,0.15 MPa, the internal friction angle is 0 °, 5 °, 10 °, 15 °, 20 °, 25 °, 30 °, 35 °, 40 °, 45 °, the tensile strength is 0,0.001,0.005,0.010,0.015,0.020,0.025,0.030,0.035MPa calculation conditions. The results of plastic zone and unbalance force in different working conditions show that the failure mode of the tunnel is not the initial lining, the main failure mode of the tunnel is the top of the tunnel. The critical value of the cohesion of the initial lining is 0.08MPa, The critical value of the friction angle is 20 °, and the critical value of the tensile strength is 0.03 MPa. If the strength is lower than these values, the plastic zone of the tunnel expands and the unbalanced force is larger, which indicates that the tunnel is not stable. These can be used as design reference.