Dynamic Response Characteristics Of Permeable Asphalt Pavement Under Multi-field Coupling

In the rainy areas in China,the common disease of asphalt pavement is water damage.The effect of water on the pressure of pore water and vacuum suction under the repeated action of vehicle load.It reduces the adhesion of the asphalt pavement structure and loses the cohesive force between the aggregate,thus causing the asphalt film to fall off the aggregate surface,which will exacerbate the damage of asphalt pavement water.The rational design of the waterproofing and drainage system is an important method to reduce the water damage.The hydraulic coupling mechanism of the asphalt pavement in the drainage design is not clear yet.What's more,the research on the dynamic response mechanism of the asphalt pavement under two states of full water and non full water has not been done with the effect of traffic load and temperature load.The fatigue damage mechanism and reliability analysis of asphalt pavement are also rarely reported.The solution of these problems above will directly affect the hydraulic coupling mechanism and dynamic response characteristics of the asphalt pavement.Therefore,the dynamic response mechanism of permeable asphalt pavement under hydro-mechanics coupling,coupled thermo-hydro-mechanics coupling and air-hydro-mechanicscoupling is studied.Based on the assumption of the elastic porous media and the Biot consolidation theory,a finite element model of the three-dimensional asphalt pavement system structure is established.The stress,displacement and pore water pressure of each structure layer are obtained by finite element numerical simulation.By analyzing the influence of various physical parameters,the mechanism of water damage can be revealed,providing theoretical basis and technical guidance for the design of permeable asphalt pavement.The main contents of this paper are as follows:(1)Study on dynamic response of permeable asphalt pavement under hydro-mechanics coupling.A three-dimensional finite element model of Saturated Asphalt Pavement is established under the action of moving load.The dynamic response of the saturated asphalt pavement is simulated and the dynamic response law of the pavement is calculated and analyzed such as the law of time history of pore water pressure,vertical displacement of pavement,vertical stress and lateral stress.In addition,the influence of the pavement parameters on the dynamic response of the saturated asphalt pavement is analyzed.The velocity has little influence on the pore water pressure of the saturated asphalt pavement,while the axial load has a great influence on the pore water pressure.When the load increases 50%,the pore water pressure increases by 59.8%,indicating the increase of axle load will aggravate the damage of pavement water.(2)Study on dynamic response of permeable asphalt pavement under thermo-hydro-mechanics coupling.A three-dimensional asphalt pavement finite element model is established for the coupling effect of temperature,water and moving load.The dynamic time history response of Saturated Asphalt Pavement is simulated under the combined action of moving load and temperature load based on multi physics coupling analysis software COMSOL.The dynamic response law of the inner surface of the pavement,the vertical displacement of the pavement,the vertical stress and the lateral stress,were calculated and analyzed.And the increase of temperature will increase the lateral tensile stress of the pavement.(3)Study on dynamic response of permeable asphalt pavement under hydro-air-mechanics coupling.A three-dimensional finite element model of unsaturated asphalt pavement structure is established by COMSOL software,based on unsaturated seepage theory.The dynamic response of unsaturated asphalt pavement under the action of moving load is calculated,and the results are compared with the results of Saturated Asphalt Pavement.The results show that the maximum transverse stress of the non saturated asphalt pavement is about 150kPa,and the maximum transverse stress of the asphalt pavement is about 800kPa,which indicates that the drainage of water plays a great role in avoiding cracks.The maximum pore water pressure of the non saturated asphalt pavement is 56.76kPa,which is 40.70%lower than that of the Saturated Asphalt Pavement under the same condition.Through analyzing the dynamic response of permeable asphalt pavement under hydro-mechanics coupling,thermo-hydro-mechanics coupling and hydro-air-mechanics coupling,the mechanism of water damage is revealed,which provides theoretical basis and technical guidance for the design of permeable asphalt pavement.