隧道复合式衬砌初期支护极限状态模型试验研究

当前既有以及新建的隧道结构大多采用复合式衬砌形式，在长期使用过程中，初期支护不可避免会出现劣化甚至失效的情况，会对隧道结构整体的承载力及耐久性造成影响。通过室内模型试验，采用可劣化的石膏模型制作初期支护的各构件，对其劣化失效过程进行模拟，记录二衬结构的状态变化，再通过增加荷载确定隧道结构整体承载力的变化情况。试验结果显示，钢架和喷射混凝土层的劣化对二衬结构的影响要比锚杆劣化的影响大得多，然而单纯的初期支护失效并不会造成二衬结构的破坏，且二衬结构还有较大的安全余度；初期支护构件劣化都会造成隧道结构整体承载力的降低，锚杆的影响最为明显，钢架及喷射混凝土失效对整体承载力降低影响不大。

Model testing research on limit state of primary support in composite lining tunnels

The composite lining is the most frequently used form of lining in new tunnels and existing tunnels. The situation, which is the deterioration or even failure of primary support, will appear inevitably in the long-term operation; and it will reduce the bearing capacity and the durability of the tunnel system. Based on indoor model test, the members of primary support are made by deteriorated gypsum model. The deterioration process is simulated and the state change of secondary lining structure is recorded. The variation of bearing capacity of tunnel is determined by increasing load. The results show that the deterioration of steel frame and shotcrete layer has larger impact on secondary lining structure than the bolt deterioration. Failure of the primary support does not result in destruction of the lining structure; and the secondary lining has adequate safety redundancy. The deterioration of primary support members will reduce the bearing capacity of the tunnel structure system. The effect of anchors is obvious, but the effects of steel frame and shotcrete layer are little.