Research On Dynamic Deflection Testing And Semi-rigid Pavement Structure Applicability Of Hangzhou Municipal Roads

Under the applying of repeated vehicle loads and natural factors on erosion, and the dramatic increase of the traffic volume and heavy vehicles in recent years, urban roads facing a widespread reform situation. Performance evaluation of the existing pavemenst structure is the base of roads reconstruction and maintenance, the core task of pavements performance evaluation is reasonably and accurately estimate the parameters of the modulus of each original asphalt pavement layer for the evaluation of structure bearing capacity. Compeleted pavements are subjected to constantly changing climate, while the asphalt is temperature sensitive material and the modulus change with the temperature; And in the process of using the road structure will gradually fatigue damage, the modulus of base will decrease. Based on this situation and the hangzhou urban road reconstruction project and national natural science fund project (51078331),the study mainly analyzes the dynamic deflection response of pavement under the FWD dynamic load in high temperature conditions.this paper also analyzes the design method and performance of reconstruction semi-rigid base asphalt pavement.Firstly the paper analyzed FWD deflection testing data of several main roads in the city of hangzhou, through the software EVERCALC back calculation the modulus of each road structure layer, and contrastive analysis the equivalent modulus of subgrade through experience regression formulas and EVERCALC to show that the method for determining the modulus of subgrade in hangzhou urban road reconstruction project is available. Then using ABAQUS modeling analysis the temperature field of Hangzhou asphalt pavement in high temperature conditions, concrete analysis dynamic deflection response under asphalt pavement modulus inhomogeneity caused by high temperature, different degrees of decay of semi-rigid base modulus and interlayer contact state several situations. Finally provides a nomograph design method for typical semi-rigid base asphalt pavement structure, and through the field monitoring and numerical analysis study the tensile strain and earth pressure at the base’s bottomwith the change of time, show that this structure of pavement is available for this project.This study may provide the basis for subgrade bearing capacity evaluation of road reconstruction projects and optimization design of pavements.