Multiplayer Viscoelastic Stress Analysis Of Asphalt Pavement Effected By Vertical And Horizontal Load

There is rutting break in highway in recent years in china, mostly it happens on upgrade section when temperature is high, most of the rutting comes from shear break. The potential reason of this rutting is increased shear stress arose by horizontal load and the asphalt concrete shear strength influenced by temperature and load time. The high temperature and long load time makes the material more viscosity and reduces the shear strength.Base on the multilayer viscoelastic theory, the stress calculating program is writed by calling the multilayer elastic stress calculation subprogram writed by Professor Dazhi GUO. Analysis the distribution of max shear stress effected by vertical and horizontal load, and the influence of load time, temperature, base course modulus and base course thickness.The conclusion is that horizontal load mainly influences the top of asphalt pavement. The shear stress distributes dissymetrically, it waves obviously on horizontal way near the surface. The max shear stress appears at the edge of load, it is bigger than the shear stress in middle part of asphalt pavement. It is essential to consider the area and occur time of max shear stress when analysis the rutting. The max shear stress is increased while the modulus and thickness of the base course is increased. The temperature and load time influences both the characteristic of materials and the max shear stress. The max shear stress is reduced while the temperature and load time is increased, at the same time the characteristic of asphalt concrete approaches the viscosity and the shear strength is lower. The affection of load time is more obviously when the temperature is high, this is the main reason that the rutting is serious in upgrade section of highway.