Research On Interlayer Adhesion Performance Of “EA+SMA” Steel Deck Pavement Structure

“EA+SMA”steel deck paving structure has gradually become the main choice for steel deck paving due to its scientific and reasonable design concept.As a double-layer heterogeneous pavement structure,the interlayer adhesion performance is critical.When the structure has poor adhesion between layers and weak resistance to shear or drawing,it will lead to failure of the adhesion between layers,resulting in diseases such as delamination,which will reduce the composite effect of the double-layer pavement structure and accelerate the destruction of pavement structure.Therefore,the research on the interlayer adhesion performance is of great significance to ensure the durability of the pavement structure.In order to determine the ultimate bearing capacity of the pavement bonding interface and explore the damage of the bonding interface under load,this paper develops research on interlayer adhesion properties of the composite structure from the three aspects of the mechanical properties,the effect of the construction effect and the interlayer bonding state.First,based on the actual characteristics of the"EA+SMA"pavement structure,a test plan for the interlayer adhesion performance including the pull-off test and the direct shear test was developed to investigate the evolution of the mechanical response of the adhesive layer under loading and the fracture morphology of the interface in the limit state,the change trends of the evaluation indexes such as pull-off/shear strength,pull-off/shear stiffness,and pull-off/shear fracture energy were analyzed.The results show:when the amount of epoxy resin adhesive layer oil is 0.5～0.6kg/m~2,the pull-out strength of the composite structure is higher;when the amount of epoxy asphalt adhesive layer oil is 0.8kg/m~2,the composite structure has the highest pull-out strength;the shear strength does not change significantly with the increase in the amount of binder;the pull/shear stiffness is less affected by the change in the amount of binder;the change trend of drawing fracture energy with the amount of binder is similar to that of drawing strength,and the shear fracture energy will gradually increase with the increase of the amount;temperature and water immersion have a greater impact on the pull-off performance of the composite structure,and a relatively small effect on the shear performance.Second,this paper selects three core elements(the curing time of EA layer,the construction defect of the adhesive layer,and the construction temperature of SMA layer)in construction process,combined with the interlayer adhesion performance test,to quantitatively analyze effect of each element on the interlayer adhesion performance.The results show that the interlayer shear strength of the composite structure gradually decreases with the increase of the EA curing time,and the interlayer pull-off strength increases first and then decreases with the increase of the curing time.The degree of weakening of interlayer adhesive properties by oil is relatively large,and the degree of weakening of adhesive properties by dust is relatively small.When the temperature of SMA construction fluctuates within the range of construction requirements,the effect on the interlayer adhesive performance of composite structures isn’t obvious.Final,ABAQUS was used to establish a numerical simulation model of the pavement structure to explore the damage of the bonding interface.Analyzing the stress and strain of the bonding layer under single failure mode and mixed failure mode based on CZM;comparing the simulation results under different damage initiation criteria and damage expansion criteria in the cohesion model,and using the damage variables as indicators to evaluate the trend of damage changes;comparative analysis of the influence of the CZM and the completely continuous between two different characterization methods on the internal response of the pavement structure.The results show that the bilinear model and the linear-exponential model are good for the simulation of the interface pull test,but have certain limitations for the simulation of the shear test;when using CZM to characterize the interlayer bonding state,the maximum shear stress between the structural layers is reduced by about 9.3%compared with the complete continuous condition,and the calculated maximum tensile stress on the pavement surface is increased by 16.2%.Aiming at the focus of interlayer bonding performance of"EA+SMA"pavement structure,the study carried out the research of interlayer bonding mechanical properties,construction influencing factors and interlayer bonding damage research,and explored the impact of different factors on interlayer bonding to ensure that the durability of the pavement structure can meet the requirements.Relevant research conclusion can provide reference for pavement structure design,mechanical analysis and actual construction.In order to improve the analysis of the bonding characteristics between the layers of the structure,the fatigue characteristics of the bonding interface can be studied later.