Research On Water Damage Of Asphalt Pavement Based On Pore Water Pressure

The water damage of asphalt pavement seriously affects the pavement performance and service life of asphalt pavement.The root cause of water damage is the stagnant water in the asphalt pavement structure,which produces pore water pressure under the action of vehicle load.The positive and negative circulation of the pore water pressure erodes the asphalt mixture and causes the asphalt to peel off from the surface of the aggregate.As a result,the asphalt mixture is loose and its strength is reduced.In this paper,ABAQUS finite element software was used to simulate numerically.The distribution law and influencing factors of pore water pressure were studied.The causes of asphalt mixture water damage were analyzed by combining the asphalt-aggregate interface adhesion characteristics and the permeability of asphalt mixture.Firstly,the AC-13,SMA-13 and OGFC-13 Marshall samples were made.The void fraction and permeability coefficient of different specimens under different osmotic pressure were measured,and the influence of voids and osmotic pressure on permeability coefficient was analyzed.The test results show that the permeability coefficient increases with the increase of the voidage,while the permeability coefficient decreases with the increase of the osmotic pressure.The permeability coefficient is also related to the gradation of the minerals.Secondly,hydrodynamic scouring test was performed on the mixed sample to study the influence of dynamic water scouring on the permeability and water stability of the asphalt mixture.he permeability coefficient of the asphalt mixture before and after flowing water was measured.The test result surface: The permeability coefficient increased with the increase of the hydrodynamic pressure and the action time.The water-saturated Marshall test and freeze-thaw splitting test were performed on the specimens after dynamic water flushing.The results show that the dynamic water erosion will reduce the water stability of the asphalt mixture,and the MS0 and TSR decrease with the increase of the moving water pressure and the action time.Thirdly,based on the fluid-solid coupling theory of porous media,a three-dimensional asphalt pavement model was built using ABAQUS finite element software to simulate the dynamic response of asphalt pavement under vehicle loads,and the pore water pressure distribution and influencing factors were studied.The simulation results show that the void water pressure,vertical displacement and maximum principal stress of asphalt pavement are fluctuating under vehicle load;the pore water pressure increases with the increase of load and vehicle speed,the pore water pressure decreases with the increase of permeability coefficient and elastic modulus.Then,the influencing factors of the asphalt-aggregate interface adhesion characteristics were studied through the indoor pull-out test,and the interface bond characteristics of the asphalt-aggregate were characterized by the pull-out strength.The test results show that at low temperature(0℃),the asphalt-aggregate interface is destroyed by adhesion,and at the normal temperature(20℃),the asphalt-aggregate interface is destroyed by cohesive failure.There is an optimal pitch film thickness that maximizes the asphalt-aggregate interface bond strength.With the increase of temperature,the bonding strength of the interface decreases,and the effect of water will also reduce the bond strength of the interface.Finally,combined with the pore water pressure simulation calculation results and the asphalt-aggregate interface bond strength,the damage of asphalt mixture under different conditions was analyzed.The analysis results show that the pore water pressure at 40°C obviously larger than the interfacial bond strength,the interface will be damaged;the pore water pressure will increase with the increase of the vehicle load.When the load increases to 0.9MPa,the pore water pressure is greater than the asphalt-aggregate interfacial bond strength,which will generate the interface destruction;pore water pressure increases with increasing vehicle speed.When the vehicle speed increases to 100 km/h,the pore water pressure is greater than the interfacial bond strength between 70# matrix asphalt and HVA high viscosity modified asphalt,which will cause interface damage.It is considered that when there is water in the asphalt pavement,the pore water pressure in positive and negative circulation will appear in a short time under the action of vehicle load,which will cause damage to the asphalt-aggregate interface and cause water damage to the asphalt pavement.Heavy load,high speed,and high temperature are the unfavorable conditions for water damage caused of asphalt pavement.