| Currently spray film waterproofing lining(CSL lining)has attracted widespread attention,but for the spray film waterproofing materials,spray film waterproofing lining interface characteristics and performance of the research is very limited,due to CSL lining in the layer has obvious bonding characteristics,in the design of the original double-layer lining design method is obviously unreasonable,which hinders the application and development of spray film waterproofing lining.In this paper,by carrying out the basic mechanical properties of spray film waterproofing materials test,waterproof membrane-mortar substrate interface bonding test,to explore the impact of different water-cement ratio,maintenance time,thickness and other conditions on CSL lining performance.Using indoor test data,the mechanical characteristics between the waterproofing membrane and mortar layer were simulated based on the cohesion zone model to verify the feasibility of the cohesion zone model in CSL lining.The composite effect of CSL lining was studied by establishing a four-point bending model,and finally a three-dimensional simulation model of CSL lining was established based on the engineering background to analyze the distribution of stresses and internal forces,and the main research contents and results include:(1)To study the impact of different water-cement ratio and maintenance time on the mechanical properties of waterproof membrane materials,tensile strength,modulus of elasticity and elongation at break three parameters selected in the tensile test to evaluate the change in mechanical properties of waterproof membrane,found that maintenance time and water-cement ratio on waterproof membrane material tensile performance has an important impact;in the waterproof membrane material compression test,the maintenance time on the elastic modulus and compressive strength,with the maintenance time increases,the elastic modulus and compressive strength is a linear relationship growth.(2)To define the relationship between the mechanical properties of the interface between the waterproofing membrane and the mortar substrate under different thickness and water-cement ratio conditions,and to provide parameter support for the subsequent cohesion zone model,this paper carried out interfacial bonding-tensile test and interfacial bonding-shear test.In the interface bonding tests conducted,parameters such as interfacial normal stiffness,interfacial tensile strength,shear fracture energy,and shear stiffness were selected for the study to evaluate the effect of waterproofing layer thickness and water-cement ratio on the mechanical properties of the interface.(3)To effectively characterize the mechanical characteristics of the waterproof membrane material in ABAQUS,a three-dimensional numerical simulation model using the elasto-plastic principal structure was established based on the uniaxial tensile test parameters.The results prove that the use of elastic-plasticity principal structure can effectively respond to the actual tensile behavior of waterproofing membrane materials;the use of cohesion zone model to establish a three-dimensional numerical model of interlayer bond-shear test,the damage process and the feasibility of the cohesion zone model was verified;by establishing a four-point bending model with spray film waterproofing layer,it was verified that the use of cohesion zone model to represent the bonding characteristics between the waterproofing layer and the substrate,can be a good characterization of the beam specimen force characteristics.By building a numerical model of a beam with a waterproofing layer(Beam B)and a beam without a waterproofing layer(Beam A),stress distribution and load capacity variation of the two beams were investigated.Finally,the effect of interface stiffness on the degree of composite of Beam B was investigated.(4)Using the parameters obtained from the indoor tests and relying on the actual engineering background,a three-dimensional model of CSL lining and DSL lining was established based on the load-structure method and cohesion zone model.The analysis results show that the stress values generated on the CSL primary and secondary lining are much closer on the selected critical sections.This is due to the bonding characteristics of the waterproof membrane,resulting in synergistic stresses between the CSL primary support and the second liner,forming a composite load-bearing structure,making the stresses and bending moments on the CSL second liner significantly reduced.Therefore,in practice,the CSL lining makes full use of the primary support under the composite load-bearing effect,thus improving the structural efficiency and reducing the thickness of the second liner. |
