Mechanical Properties Analysis Of Asphalt Concrete Pavement Under Heavy Traffic

Semi-rigid asphalt pavement has been widely used in the country because of its advantages at present, but also produced all kinds of issues such as widespread early damage, shorter life than the design. With the rapid development of transportation, overrun and overloaded transport phenomenon grow much, which make our asphalt pavement rutting, cracking and other phenomenon increasing common. Currently, the road structure design is still based on static load, but the design method can not reflect the dynamic characteristics of the road. Indeed the load that pavement suffered is changing and moving when vehicle in motion, uneven pavement, the vibration of the vehicle itself and the vibration of vehicle and road coupled system will cause changes in load, thereby affecting the force of the road. Therefore, the dynamic response analysis of asphalt pavement under heavy load has practical significance.Based on the layered elastic theory, using the sinusoidal vibration vehicles load model under two degrees of freedom, I establish a simplified three-dimensional finite element model for the pavement structure of Puxuan Expressway in coal areas in Yunnan. The model in the standard axle load and varying degrees of role overload were analyzed and obtained the dynamic response trends and patterns of pavement structures under moving loads. On this basis, briefly analyzing the effects of the speed and temperature on and dynamic response. In addition, by comparing the analysis and calculation of response of pavement under static load and dead load get that dynamic load is more in line with the actual situation. In order to get a reasonable asphalt pavement under heavy traffic, analyzes the variation of important mechanical response indicators under overloading 80% of dynamic load wih the changing of surface layer thickness, base layer thickness, the thickness of subbase, base layer modulus, modulus of subbase and subgrade modulus, and make reasonable suggestions to the Puxuan Expressway. The main conclusions are as follows:The dynamic response under heavy load effect are more significant increscent, and with the overload rate showed a linear growth trend, overloading become one of the early serious damage reasons of high-grade road, road fatigue life is also severely reduced; The dynamic response was reduced in the overall trend in response to the increasing of speed, when the speed increased to a certain value, each dynamic response tend to be stable; temperature affect the material properties of the asphalt surface, thereby affecting the dynamic response indicators, when the temperature rises, the vertical displacement of the surface layer, the compressive stress and the vertical and horizontal tensile stress increases, when the temperature decreases, the maximum horizontal shear stress of the surface layer decreases.Deflection, the crushing stress of surface layer, the tensile stress under the bottom of surface layer, horizontal shear stress and the compressive strain on top of subgrade all decrease with the increases both in the thickness and the modulus. But the base bottom tensile stress with the increase of base course modulus will increase in different degree, which subbase thickness is its greatest impact; base layer bottom tensile stress will increase with the subbase layer modulus increasing. It is easy to know that each structural layer parameters have a different influence to indicators the mechanical design and checking related to, so it is important to considering all the material parameters and thickness of structure layer when designing the structure of asphalt pavement under heavy load.