Design Of Laboratory Circular Track System And FEM Simulation Of Circular Track Rutting Test

The system of the indoor circular track laboratory of Civil Engineering, Hunan University was designed; the influencing factors of the circular track rutting test and the impact of the base layer thickness and type on rutting development of asphalt concrete pavement was analyzed; the rutting changing law of Semi-rigid asphalt concrete pavement at various loads was analyzed. The FEM analysis results show that the circular track rutting test is few impacted by the confinement of the earth subgrade thickness and pavement width, the restriction of the earth subgrade bottom boundary and the lateral restriction of inside an outside wall of the circular track, so it can reflect the development of pavement rutting in true status; The rutting development is few impacted by the reducing of base layer thickness; The rutting of the flexible base pavement and semi-rigid base pavement is to some tune; Asphalt concrete surface deformation mainly occurs in the middle and under surface layer. Therefore, it can ignore the impact of the confinement of the earth subgrade thickness and pavement width, foundation stiffness and the lateral restriction of inside an outside wall of the circular track; After ignoring the deformation of cement stabilized macadam base and checking the bottom tensile stress of the asphalt surface layer and semi-rigid material layer, it can properly reduce the base layer thickness in view of the height of circular track testing trough in circular track rutting testing; It can deduce that the flexible base pavement can achieve good effect of anti-rut by contrasting rut of the flexible base pavement and semi-rigid base pavement; To control the rutting of asphalt pavement, it will have to raise the level of resistance to rutting of middle and under surface layerAsphalt concrete pavement reinforced with grid can effectively stay the production of the rutting, it change the partially force of the pavement through laying the grid in asphalt concrete pavement, to achieve the objective of reducing rutting. The anti-rutting performance of asphalt concrete pavement reinforced with grid is researched, on the one hand by the rutting test of asphalt mixture reinforced with grid, on the other hand by structural mechanical analysis. In the structural mechanical analysis, previous research is more to establish elastic or elastic-plastic model to study the grid reinforced effect on pavement stress and deflection.In order to make study of grid reinforced asphalt surface layer on impact of rutting development, this thesis established visco-elastic-plastic mechanical model of grid reinforced asphalt pavement structure. The model took into account the actual temperature of asphalt pavement structure layers (temperature changes as the structure depth increases) and creep effects of asphalt concrete. The model used a typical high-temperature field, simulated and analyzed the rutting changing law of the pavement structure with or without additional geo-grid as ground pressure changed, the reinforced position of grid changed and the grid modulus changed. The results show that the asphalt pavement reinforced with glass fiber grid can well reduce the rutting and the rutting increases small even in high temperature and overloading; the best reinforced location of asphalt concrete layer is the upper layer, where the grid can well withstand the shear stress of asphalt concrete surface and reduce Shear Rheology to achieve the purpose of reducing rutting; the grid reinforcing effect increases as the modulus increase. Therefore, in a section of a highway with high pavement temperature, overloading and heavy traffic, laying a layer of glassgrid in the bottom of the upper layer of asphalt concrete can well reduce the development of rutting.