Rutting Analysis Of Composite Pavements For Expressway

With the rapid development of expressways in China,the focus of highway construction has gradually shifted from the developed plains to the hilly areas.The road surface disease of long and steep slope sections of mountainous expressway has become an unavoidable problem.As the terrain of the expressway is repeated,the longitudinal slope is relatively large,the number of large longitudinal slope sections is large,and the disease phenomenon is more serious than the ordinary section under the influence of many external factors,such as high temperature,overloading and low speed.In this paper,the mechanism of rutting and the factors that affect rutting are studied in detail.The finite element analysis software is used to simulate the situation of vehicle through the highway composite pavement with large longitudinal slope,and a reasonable compound pavement structure model is set up.The mechanical analysis and rutting prediction of the composite pavement under different conditions are carried out.First,the temperature model of the pavement temperature field is set up to simulate the rutting prediction model of the composite pavement,and the change rules of the rutting of the asphalt layer on the axle load,speed,the thickness of the asphalt layer and the thickness of the concrete board are studied,and the important factors that affect the rutting are deduced.The results show that the axle load and speed of vehicle have great influence on the production of asphalt rutting.The thickness of the asphalt surface and the thickness of the concrete plate have a certain influence on the rutting production.Controlling overloading phenomenon can effectively reduce the occurrence of rutting.Reasonable selection of pavement structure can reduce project cost and rutting volume to a certain extent.Then,the rutting prediction model of asphalt pavement is simulated,and the changes of asphalt pavement and composite pavement rutting are compared to reflect the anti rutting performance of the asphalt pavement and the anti rutting performance of the composite pavement.The results show that the flexural tensile strength of the cement concrete slab is large,and the stress effect is basically borne by the plate body.The pressure transferred to the basic unit is small.The internal shear stress produced by the concrete is larger than the asphalt pavement,and the anti rutting performance of the composite pavement is weaker than that of the asphalt pavement.Finally,the influence of the vehicle on the composite pavement structure under the condition of uniform speed and braking is analyzed,and the influence of vehicle braking on rutting is determined.The results show that all indexes of pavement mechanics under vehicle braking condition are greater than that of vehicle under uniform speed.Reasonable and effective design of road slope plays an important role in slowing down rutting.