Effects Of Freeze-thaw On Surface Crack Propagation Of Asphalt Pavement And Finite Element Analysis

Asphalt paving is the main form of paving of high-grade highways in China.It has the advantages of construction convenience,driving comfort and easy maintenance.The crack problem of asphalt pavement is the main factor causing the destruction of asphalt pavement,which is commonly found in all stages of the life of asphalt pavement.In the frozen regions of northern China,freezing and thawing effects have a greater impact on the surface crack propagation of asphalt pavements.Currently,studies on the effects of freeze-thaw on crack propagation have mostly been theoretical and FEM simulations,and there have been few experimental simulations.Indoor experiments and finite element modeling analysis have more comprehensively studied the effect of freeze-thaw on the surface crack propagation of asphalt pavements.Firstly,based on the related theory of linear elastic fracture mechanics,the common fracture modes and crack propagation mechanisms are analyzed and summarized,and the formula of the stress intensity factor is deduced.Secondly,with reference to the actual engineering conditions and the test specifications of asphalt mixture,a reasonable indoor freeze-thaw cycle test was designed to determine the temperature of freeze-thaw cycle test,test piece size,influencing factors,and evaluation indicators.Check the raw materials of asphalt mixture,and design the mix ratio of four types of asphalt mixture.Freeze-thaw test pieces were prepared according to the test plan,and the indoor freeze-thaw cycle test was conducted.The statistics of the test results were analyzed to analyze the effect of crack size on the degree of crack propagation under freeze-thaw cycles.Four types of asphalt mixture trabecule specimens were prepared and subjected to bending test to analyze the low-temperature crack resistance of four gradations under the action of freeze-thaw cycles.The SPSS 19.0 data analysis software was used to calculate the variance of the test results for three times,and analyze the influence degree of each factor and level.Finally,based on the theory of linear elastic fracture mechanics and the finite element method,a two-dimensional numerical model for asphalt pavement with cracks is established.The plane is divided by a singular unit with eight nodes.Calculation and analysis of the effect of crack depths,crack widths,materials,etc.on crack propagation of asphalt pavements under freeze-thaw cycles.Under the corresponding parameter variables,the crack cracking tendency is studied and combined with indoor test results to provide reasonable suggestions and theoretical references for crack protection and prevention of asphalt pavement.