Research On The Interlaminar Interface Bond Slip Characteristics Of Spray-applied Waterproofing Lining

The characteristics of the tunnel Spray-applied Waterproofing lining structure are that the film is sprayed between the first branch and the second lining of the tunnel to form a flexible waterproof layer,which is fitted with the first branch and the second lining and has a certain bonding strength.Due to the existence of the membrane waterproof layer,the tangential stress between the primary branch and the secondary lining can be transferred to a certain extent.The waterproof layer may fail under the action of the stress,and the interlayer interface of the lining may also break away and slip,thus causing a non-negligible impact on the overall bearing capacity of the lining structure.In order to explore the mechanical and failure characteristics of the interlayer interface and the waterproof layer,the mechanical properties of the spray film waterproof layer material and the CSL structure interface were studied by experiments combined with numerical simulation.(1)The mechanical properties of waterproof materials were tested.Three grades of polymer cement waterproofing materials were selected as samples to make films.Uniaxial tension,plane tension and biaxial tension tests were carried out to obtain the mechanical properties of the materials under uniaxial tension,plane tension and biaxial tension.The experimental data were processed with ABAQUS finite element software to fit the constitutive model,and the rationality of the fitting results was verified.(2)The interfacial bonding and shear tests were carried out to study the interfacial bonding-slip characteristics of concrete and waterproof materials.Firstly,the interface bond-failure characteristic curve between three grades of waterproof material and concrete was obtained by bonding test.Secondly,the interfacial shear test and test device of CSL structure are designed.The shear-slip mechanism and failure law of CSL structure interface are analyzed through test.According to the test,the interfacial shear modulus,shear strength,residual shear strength,shear-slip energy and other parameters are obtained.The failure modes and failure laws of the interface are analyzed.(3)Combining with ABAQUS finite element software,the cohesion model is used to simulate the bonding layer between concrete and waterproof material,and the finite element model of initial supported concrete-bonding layer-waterproof material-bonding layer-secondary lining concrete is established.The variation,distribution and failure mode of interfacial stress in different compressive shear stress states were analyzed and compared with the experimental results.The results show that the cohesive force model can effectively simulate the mechanical deformation and failure characteristics of the CSL structure interface by using appropriate constitutive model of waterproof layer material and selecting reasonable interface parameters.