| Porous asphalt pavement has good skid resistance,which provides safety guarantee for vehicle driving in rainy days.In rainy weather,a layer of water film is formed on the road surface,which reduces the friction coefficient of the road surface.At the same time,the tire is lifted by the hydrodynamic pressure of the water flow,resulting in an upward movement trend.The adhesion of the road is reduced,and the braking distance required for emergency braking when the vehicle encounters danger increases.In rainy days,the road driving should control the driving distance and set aside a certain braking distance to avoid the rear-end failure of the braking.When the vehicle speed is too high,the separation of the tire from the road will eventually lead to water slide.It is difficult for drivers to perceive and predict the water slide of the tire,and it is easy to slip and lose control of the vehicle.Therefore,driving in rainy days should maintain a certain safe driving speed,and take the vehicle speed as a reference to avoid tire slip.For Porous asphalt pavement,because of its excellent drainage capacity,it is different from ordinary dense graded asphalt pavement,and it will show good anti-skid performance in rainy days.In order to facilitate the popularization and application of Porous asphalt pavement technology,this paper studies the influence of different factors on vehicle skidding speed through finite element simulation,analyzes the tire skidding speed and braking distance of different asphalt pavements under different rainfall intensities,puts forward the control standards of safe driving speed and vehicle distance of Porous asphalt pavement in rainy days,and reveals its anti-sliding mechanism.Based on the CEL fluid-solid coupling theory,the tire-road-water coupling model was established by ABAQUS finite element simulation software.According to the experimental results of other researchers,the relationship between water film thickness and rainfall intensity was obtained.With the water film thickness as the reference,the falling water velocities of OGFC and SMA asphalt pavements with different rainfall intensities distinguished by friction coefficients are explored,and the safety speed standards are proposed respectively to analyze their anti-sliding mechanism.The influence of tire inflation tire pressure and tire load on slip velocity and the influence of vehicle speed on contact pressure between tire and road are studied.The results show that the sliding speed of the tire decreases with the increase of rainfall intensity,and increases with the increase of tire inflation tire pressure and load.The higher the vehicle speed,the lower the contact pressure between the tire and the road,and the decreasing trend is accelerated with the increase of rainfall intensity.Due to the good drainage performance of permeable asphalt pavement,the lifting force of road surface water on tires can be greatly reduced,and its high friction coefficient ensures its good skid resistance compared with dense graded asphalt pavement in rainy days.Therefore,it can set relatively high safe driving speed standards.The braking process is discretized and the reasonable slip rate is set to solve the relevant limitations of ABAQUS for the realization of tire ABS braking.Considering the calculation time,a speed interval in the braking process is selected to solve the braking time,and the braking distance of the whole process is predicted.The braking distance under different rainfall intensities and initial braking speeds is analyzed,and the safe vehicle speed model is established.The safe driving distance standard of permeable pavement is proposed.The results show that the braking distance of the vehicle is greatly affected by the initial braking speed and rainfall intensity,and increases with the increase of the initial braking speed and rainfall intensity.The safe distance proposed according to the safe driving distance model under the static state of the front vehicle can fully ensure the driving safety. |
PDF Full Text Request