Traffic Loads Subgrade And Dynamic Finite Element Analysis

Modern highway transportation requires that pavements should be well built, so that vehicle can not only pass unhindered in any weather but also pass safely, cozily and economically with a high speed. This asks highway engineering for higher quality.Current design method of pavement surface and subgrade uses a mechanical model of clastic multiplayer system by vertical static load. This does not accord with the fact. Vibration is often caused by vehicle runs on the roads because pavement irregularity. The force that is given to the road changes with time and road face characteristics, it is a typical dynamic load. With the development of economy and transportation in China, traffic volume, vehicle speed and vehicle loading are increasing. So it is a necessary tread that the theory of pavement design changes from a static system to a dynamic system.In this paper the dynamic response to subgrade of highway under automobile load is researched.In the paper a simple exciting load, which can reflect periodicity and geometric irregularity, is proposed to simulate the vertical dynamic load of the automobile. Asphalt surface course and base course are considered as linear-elastic material; earth subgrade and earth foundation are considered as elastic-plastic material. Based on this, a mechanical model is established and an elastic-plastic dynamic finite element program with the MATLAB language is made. Using non-linear numerical analyses, this paper researches the dynamic stress and the acceleration's attenuate law on road subgrade and the subgrade dynamic stress's response by vehicle speed, base course stiffness, road irregularity and vehicle loading. And subgrade settlement and permanent deformation by automobile load are also researched. At last, the paper gives some conclusions which can be used in design, building operations and management of highway engineering.