Construction Defect And Reinforcement Effect Evaluation Of Lining Of Diversion Tunnle

In the process of construction for tunnel,construction quality defects are one of the important factors in the safety of tunnel and reinforcement measures often determines the safety of tunnel engineering.The damage of construction defective lining often involves stiffness and strength of lining,such as the insufficient thickness and the lack of reinforcement.However,there are relatively few reinforcement methods for quality defective lining.It is of great significance to carry out the reinforcement method of defective lining stiffness.Aiming at the insufficient strength of defective lining in type o.f III surrounding rock of the diversion tunnel in Shanxi Province,carbon fiber is put forward and checked.Aiming at the stiffness problem of defective lining in type of IV and V surrounding rock,the method of secondary reinforcement of surrounding rock by systematic bolt is put forward.The effect of reinforcement of surrounding rock by systematic bolt is equivalent to equivalent compression zone.The formula for calculating equivalent compression zone thickness of circular arch tunnel is put forward,and compared with the empirical formula of equivalent compression zone thickness.The calculation results show that the reinforcement measure meets reinforcement.The main conclusions as follows:(1)In view of the reinforcement methods of the mechanism of lining for construction quality defects,local lining reinforcement method is adopt to reinforce III surrounding rock;surrounding rock reinforcement method is adopt to reinforce type of IV and V surrounding rock,and the passive restraint surrounding rock reinforcement method of systematic bolt is put forward.The result shows that the local cracks caused by the local breakage of lining should be strengthened by the local reinforcement of lining;longitudinal and transverse cracks in lining or the lining floor collapse and uplift damage,the lining stiffness should be adopt.(2)Based on the calculation formula of equivalent compression zone thickness of linear tunnel,the formula of equivalent compression zone suitable for arch tunnel is put forward,which is consistent with the result of the method of empirical equivalent compression zone thickness.The study shows that the thickness of the equivalent compression zone is related to the length L of the bolt and the row distance D of the bolt,and has little related to the radius R of the tunnel.(3)The main problem of defect lining in type of III surrounding rock is insufficient strength.Carbon fiber is adopt to reinforce the lining.Load-structure method is adopt to evaluate the calculation and safety margin of typical defect lining.The results show that the design value of the bearing capacity of the lining in floor increases from 62.5%to 179.9%,and the design value of the bearing capacity with insufficient thickness of the wall is 66.6%increased to 145.7%,the safety margin of lining is significantly improved,and the reinforcement effect of the method is remarkable.(4)The main problem of defective lining in type of ? and V surrounding rocks is the insufficient stiffness of lining.ABAQUS is adopt to respectively simulate the stress of lining,surrounding rock and equivalent compression zone under the conditions of type of IV and V surrounding rocks.Stress analysis and safety redundancy evaluation of defective lining in type of IV and V surrounding rocks are analyzed.The results show the stress of defective lining decreases significantly adopt by bolt reinforcement.The safety redundancy of the stress of defective lining is increased by 20.8%and 32.7%(compared with the design value of concrete),43.6%and 50.9%(compared with the standard value of concrete).