Study On Interlaminar Shear Fatigue Of Continuously Reinforced Concrete Rigid-flexible Composite Asphalt Pavement

Continuously reinforced concrete rigid-flexible composite asphalt pavement is a new pavement structure that combines rigid base of high strength with asphalt concrete pavement,it has more advantages including high overall strength,driving comfort,long service life and small maintenance cost,and it is one of the development directions of the long-lived asphalt pavement structure for the heavy load traffic expressway.Cutting-slippage is the main problem of rigid-flexible composite asphalt pavement.Current research is short of the shear stress state,the rule and influence factors analysis of composite asphalt pavement under all kinds of complicated environment and conditions(uphill,downhill and bend),lack of the experimental study on shear fatigue with different interlayer combination status and material,lack of shear fatigue failure mechanism research under repeated load and temperature long-term effecting.Using the ABAQUS finite element software,calculated interlaminar shear stress of CRC+AC pavement structure,analyzed the influence law of maximum shear stress with different loading position,overload,horizontal force coefficient,thickness of AC layer and CRC layer,and modulus of AC layer.Obtained the critical loading position of maximum shear stress when the crack spacing is 1.5m,determined the relationship between the maximum shear stress and asphalt thickness when the interlayer completely continuous and the car emergency brake(f=0.5).On the basis of the structure characteristics and flaws of existing studies of rigid-flexible composite asphalt pavement,a device for interlaminar shear fatigue test is developed;it is simple in structure,easy to operate,and make full use of existing test equipment,its testing method is real and scientific,according with the actual stress state of pavement structure.Interlaminar shear fatigue tests were performed by the designed device,the optimum dosage of SBS modified asphalt as interlaminar bonding material of rigid-flexible composite pavement was determined to be 1.4kg/m2,and then conducted interlaminar shear fatigue test,obtained shear fatigue equation and proposed the interlaminar shear strength structure coefficient of rigid-flexible composite pavement.Based on the interlaminar shear fatigue test and interlayer shear stress of finite element analysis,proposed the asphalt layer thickness design method considered of interlaminar shear fatigue,and then pointed out the structure design flaws of the limited scope of coefficient ?a'of the current specifications JTG D40-2011 in overlay on old cement pavement,using software "matlab" to broad figure of the coefficient ?a',thus further improving the design method of composite pavement structure.The study results can provide reference for rational design of structure thickness of composite pavement.