Investigation On The Reinforcement Characteristic Curve Of Existing Plain Concrete Lined Of Corrugated Plate Anchor

In practical engineering,the treatment scheme for repairing and strengthening tunnel diseases often has problems such as long construction period,high cost and poor durability.Corrugated plate has many advantages,such as good ductility,long durability,high strength,convenient construction and so on.The engineering application prospect is very good.Using corrugated plate to strengthen cracked lining can effectively solve the problems existing in construction.However,at present,there is still a great gap in the theory of corrugated plate reinforced tunnel.In order to better guide the problems in tunnel maintenance and reinforcement construction and design,it is urgent to conduct a more in-depth study on the relevant theory of corrugated plate reinforced cracked lining.According to the analysis of fracture mechanics theory,the cracks of plain concrete lining are mostly open cracks and open sliding composite cracks.Therefore,according to the two types of cracks,the reinforcement test of plain concrete lining strengthened with corrugated plates under the control of two different failure modes of bending tensile force control and compression shear force control and at different crack times is set up.This paper has carried out experimental research with the support of major projects of the National Natural Science Foundation of China,A total of 10 groups of plain concrete members were poured.The indoor loading test was carried out based on the Key Laboratory of the Ministry of education of traffic tunnel engineering of Southwest Jiaotong University.Through repeated loading and unloading tests,the post peak section of the member load displacement relationship curve was finally fitted in the form of hysteretic curve.The reinforcement effect,mechanical characteristics and corrugated plate reinforcement characteristics of the 10 groups of members at different crack times were studied,and the following conclusions were obtained:(1)The ultimate bearing capacity of corrugated plate can be improved in different degrees after strengthening at different crack damage times.Among them,the effect of bending tensile force control members is the most obvious when strengthening without crack damage.The bearing capacity after strengthening is 96.8% higher than that of non reinforced members,followed by the initial cracked members,and the bearing capacity is 38%;The reinforcement effect of compression shear force control members is better when the crack damage is serious.This paper explores the reinforcement effect of members with the remaining 40% bearing capacity,and the bearing capacity is 38.5% higher than that of non reinforced members.The test results show that the overall mechanical properties of members have been significantly improved under the reinforcement of corrugated plates,especially for bending tensile force control members and compression shear force control members with the remaining 40% bearing capacity,It can be inferred that the reinforcement effect of corrugated plate may be better and make full use of the material properties when the member is seriously cracked.(2)The corrugated plate has good ductility and high strength,and the deformation and crack development of the reinforced concrete members can be effectively controlled.When the reinforced flexural tensile force control members reach the ultimate bearing capacity,the radial displacement can be reduced by more than 35% compared with the non reinforced members,and when the reinforced compression shear force control members reach the ultimate bearing capacity,the radial displacement can be reduced by more than 25%;From the load displacement relationship curve,it can be seen that the stiffness of the member is effectively improved after the corrugated plate reinforcement.The use of corrugated plate reinforcement in the structure with low strength can improve the safety reserve of the member and prolong the service life of the member.(3)This paper discusses the failure process,mechanical characteristics and reinforcement characteristics of plain concrete members strengthened at different crack times.Because the change trend of load displacement relationship curve of corrugated plate reinforced structure is consistent with that of ordinary structure,a kind of reinforcement characteristic curve of corrugated plate reinforced plain concrete lining characterized by load displacement relationship is explored.