隧道不同损伤状态二次衬砌预养护试验研究

采用1∶10破坏性模型试验，研究隧道不同损伤状态衬砌预养护构件变形特性、破坏模式与承载力.研究表明：预养护试件整体破坏由原衬砌拱腰极限承载力控制；预养护损伤衬砌受力过程为“加载—原裂缝贯通—套拱拱顶裂缝贯通—试件破坏”，整体结构刚度逐渐退化.关键部位破坏顺序为“拱顶开裂—拱腰脆性断裂—拱顶延性破坏”.裂缝深度为1/3衬砌厚度损伤状态可作为合理预养护时机；不同损伤状态衬砌预养护曲率突变点一致，可作为加固构件养护控制基准；提出衬砌预养护构件破坏荷载与损伤状态关系简易计算公式，计算结果与试验误差约5%.
1∶10 destructive model tests were carried out to investigate deformation characteristics, mechanical response, crack propagation and bearing capacity of pre maintenance of cracking lining. The entire failure of pre maintenance is controlled by ultimate bearing capacity of hance of lining. The mechanical process of the reinforced lining is as follows: loading, crack coalescence of lining crown, crack coalescence of umbrella arch, and failure test. Stiffness of structure declines with the load increasing. Sequences of failure at crucial positions are cracking of vault, brittle fracture of arch hance and ductile failure of arch. When the depth of crack reaches a third of lining thickness, the damage state should be deemed as favorite time of pre maintenance. Under different damage conditions, the catastrophe point of reinforcement with umbrella arch is unanimous. It can be deemed as control criteria for maintenance of umbrella arch. A simplified formula is put forward to show relationship between failure load and damage state. The deviation is 5% approximately between the calculation results and the model test