Research On Tensile Strain Variation Of The Bottom Layer Of Layered Pavement Structure Simulation

The asphalt pavement design of China, use design deflection value and asphalt bottom stress for pavement design index. According to the research, deflection is a comprehensive index, it is difficult to exact show that the level of control and damage types, and still have some problems in the actual application. the most direct reason of pavement damage is caused by too much strain. Since the 20 th century,the permanent road reaserched by many road workers at home and abroad,with tensile strain level of surface course of the bottom layer as one of the control indicators to greatly improve the service life of road.and each countrie is trying to use bottom tensile strain as road design control index. Therefore, the research on the structure bottom tensile strain change rule has important practical significance, and provides the basis to layer structure design especially road design and road construction.The analysis the limitations of the current general analytical method and numerical analysis method in structural design the road,using the method of experimental simulation analysis layer structure bottom tensile strain change rule In this paper, at the same time using the experimental results to compare with finite element numerical calculation results, and points out the difference between them. This experiment used data information collection instruments Datataker85G, the data acquisition layer tensile strain under different conditions.Indoor experiment mainly conclusion is following:as the load increases, tensile strain size order of each bottom:Surface layer upon layer bottom longitudinal tensile strain> grassroots bottom longitudinal tensile strain>surface layer upon layer> the transverse tensile strain the bottom transverse tensile strain, In addition,increased significantly of the grassroots transverse tensile strain is small than others;when surface layer thickness reaches a certain value, continuing to increase the thickness have very small impact on the bottom layer of tensile strain;changing thickness has a great impact on the bottom layer longitudinal strain but has small impact on the bottom layer tensile strain;As the load increases,if surface layer elastic modulus is small that increased significantly of surface layer upon layer is great.Analysis of compared experimental measurement with the finite element calculation shows that:experimental results is generally similar with finite element calculation results, but in some aspects there have certain differences,these differences may be caused by the limitation of modeling and parameter selection of the finite element calculation method.