Thermo-Hydro-Damage-Mechanical Response Of Asphalt Pavement

Under the combined action of natural factors(such as temperature,moisture,etc.)and vehicle load,asphalt pavement is easy to cause significant damage and cracking.In particular,the extensive promotion of durable asphalt pavement makes the fatigue damage and cracking more obvious and prominent.Therefore,how to predict the damage trend and performance of asphalt pavement under the action of temperature,moisture and vehicle load,so as to extend its service life has become an urgent problem to be studied and solved.This paper proposes a systematic method for studying thermo-hydro-damagemechanical(THDM)coupling characteristics of asphalt pavement,including pavement temperature,asphalt pavement pore water,asphalt pavement damage and vehicle load.Firstly,the thermo-hydro-mechanical(THM)model and thermo-damage-mechanical(TDM)model of asphalt pavement were established respectively based on the coupling interaction and joint effect between temperature,moisture,damage and vehicle load.Then the concept of water damage was introduced on the basis of the above model,and finally the THDM model of asphalt pavement was constructed,which considered the combined action of temperature,moisture,damage and vehicle load.The above models are based on the implement and calculation of finite element software,and the effectiveness and accuracy of THDM model are indirectly verified from the perspectives of the mechanical properties of asphalt mixture,the temperature conduction of asphalt pavement,the hydraulic properties of asphalt pavement and the damage properties of asphalt pavement.The results show that temperature,moisture and vehicle load have significant effects on the damage evolution and performance of asphalt pavement.The tensile stress of asphalt pavement under vehicle load is the main cause of bottom damage,which is especially significant in low temperature environment.The high shear deformation caused by vehicle load makes the high temperature season a critical period for its development.Under the action of thermal expansion and cold contraction,the horizontal tensile thermal stress of low temperature asphalt surface layer is the fundamental cause of temperature damage,which makes the temperature damage develop and accumulate only in the cold season.Widespread water diffusion in saturated asphalt layer effect significantly reduced the adhesive and cohesive forces of asphalt film,at the same time,water “pumping” produced by vehicle load contributed to the stripping of asphalt.Therefore,the effect of water diffusion and “pumping” leads to the generation and development of water damage in saturated asphalt pavement.Under the action of temperature,pore water and vehicle load,failure and fracture first occur at the bottom of the surface layer,among which the hydraulic impact damage caused by "pumping" is the most significant.