The Experimental Study On Mechanical Performance Of Sprayed SHCC For Tunnel Linings Concrete Repair

Tunnel shortens the distance people travel, improves travel efficiency,offersconvenience to people’s life and also alleviates the problem of heavy traffic. However,as technology continues to develop, tunnel is also being affected by many factors suchas earthquakes, flood, debris flow, fire disasters and so on. These disasters seriouslyaffect the stability of the tunnel. The tunnel is still a half of hidden construction, whichwill increase the difficulty of maintenance and bring a lot of inconvenience to traffic.Therefore, the restoration of the tunnel should be finished in a short time as soon aspossible and repaired structure should have some durable life. However, a lot ofstructures nowadays have all kinds of problems short time after the restoration, thestructure has to be repaired again. This method is not only a waste of materials, but alsowastes a lot of manpower and time. The cost of repairing is self-evident.For the various problems faced with structural repair at present, this article putsforward the research way by combining with the PVA-SHCC results which wereresearched by the scholars and using the accelerator’s role of rapid acceleration. Addfibers and accelerator to the cement matrix. The fiber can play the role of crackresistance, seepage, tensile and impact resistance, which improve durability of thematerials. The accelerator is added to make repair material condense quickly, so as toreach the purpose of quick fixes, to make the structure into use as soon as possible andto avoid disruption to traffic. This experiment will use the liquid accelerator, test itsquality according to the standard, add different amounts of it to the PVA-SHCC toform the production of a40mm×40mm×160mm test block and measure itscompressive, flexural and four-point bending strength after conserving a certain time.Experimental results show that the accelerator effectively improves the early strengthof the material. Compared with the material which is not added accelerator, latestrength of the material has a certain degree of reduction. At the same time, acceleratorimproves the flexural toughness of the material well and improves flexural strengthof restorative material.Secondly，a very important indicator of structural repair is bonding properties ofthe interface. The condition of bonding properties is directly related to the success orfailure of repair. The tensile bond test methods will be used to determine bondingproperties of the interface. According to bonding tensile test, the more accelerator isused, the better bonding properties structured interface performs, which, to some extent, improves the success rate of repair. Finally, the repair materials is prospected，which laid the foundation for academics on the future research of structure repair.Experiment makes full use of the superiority of the fiber itself as well as thecharacteristics of accelerator, overcomes the defect of modern structure repair to someextent. Results of their research will provide some reference value for repairing theconcrete tunnel lining as well as other structure using a jet SHCC, which has importantsignificance.