Abstract: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.
