Study On Shear Stress Analysis And Interlayer Shear Resistance Of Asphalt Pavement Surface

In recent years,the mileage of asphalt pavement construction in China has witnessed rapid growth,due to the strong support of the state.However,the asphalt pavement structure often fails to meet the requirement because of the decline of interlayer bonding performance before cracks,looseness or other damage occurs,which leads to the increasing occurrence of interlayer damage of pavement.The quality of interlayer bonding performance has a very significant impact on the service life of asphalt pavement,especially in the large longitudinal slope section,small radius curve section and vehicle acceleration and braking area where the horizontal stress is more obvious in the structure layer of asphalt pavement.When the repeated action of vehicle load exceeds a certain number of times,the interlayer shear fatigue damage of asphalt pavement will occur.Therefore,it is necessary to study the shear fatigue resistance of asphalt pavement.In this paper,based on the theory of elastic layers,the stress in asphalt pavement structure is calculated and analyzed.Two typical pavement structures are simulated by BISAR software,and the distribution of shear stress in asphalt pavement structure is studied.The results show that the internal shear stress of pavement structure mostly concentrates on the surface layer,and it is more obvious near the interlayer interface.Secondly,three pavement structures(AC-16+AC-20,AC-13+AC-20 and SMA-13+AC-20)and three kinds of clay materials(SK90 asphalt,emulsified asphalt and SBS modified asphalt)were selected as the research objects,and interlaminar shear test and shear fatigue test were carried out respectively.On the one hand,the effects of different pavement structures,types and dosages of cohesive materials,temperature and freeze-thaw cycles on the interlaminar shear strength of specimens are studied;on the other hand,the effects of different stress levels,loading frequency,temperature and freeze-thaw cycles on the interlaminar shear fatigue life of specimens are studied.The results of shear strength test show that the shear strength of SK90 asphalt,emulsified asphalt and SBS modified asphalt viscose oil increases firstly and then decreases with the increase of spraying amount.The optimum spraying amount of SK90 asphalt,emulsified asphalt and SBS modified asphalt is 0.6kg/m~2,0.8kg/m~2 and 1.2kg/m~2respectively.With the same layer material,the interlaminar shear strength of SMA-13+AC-20,AC-16+AC-20 and AC-13+AC-20 decreases with the increase of temperature,showing a quadratic polynomial trend.With the increase of freeze-thaw cycles,the interlaminar shear strength of different cohesive layer specimens decreases continuously,and the reduction rate varies from large to small.Secondly,SK90 asphalt,emulsified asphalt and SBS modified asphalt.The shear fatigue test results show that under the same conditions,the shear fatigue life of specimens decreases with the increase of stress ratio,and the relationship between the shear fatigue life of specimens and the loading frequency is approximately linear.The larger the loading frequency is,the longer the interlaminar shear fatigue life of specimens is;with the increase of temperature,the shear fatigue of specimens is approximately linear.The shear fatigue life of the specimens decreases gradually with the increase of freeze-thaw cycles,and SBS modified asphalt is better than emulsified asphalt under freeze-thaw conditions,and emulsified asphalt is better than SK90 asphalt.