The Experimental Research Of Asphalt Mixture Dynamic Modulus Under Bidirectional Stress State

The asphalt pavement shoulder the actual dynamic loading during the process of operation.However,it is often subjected to the interaction of the vertical normal stress and the horizontal shear stress due to the influence of the route and the start or brake of the vehicle.The current dynamic design theory has not yet fully mature,especially the dynamic modulus under vertical uniaxial dynamic loading is considered only in asphalt pavement design which is not consistent with the actual stress state.Therefore it does have very important practical significance considering the dynamic modulus of asphalt mixture under bidirectional stress and revealing the dynamic response mechanism of the asphalt pavement.This paper adopts the vertical and horizontal direct shear dynamic loads to carry out the dynamic response test of cylinder specimen asphalt mixture,analysis the dynamic modulus under different dynamic loads and their combinations.The main contents are:(1)In view of the actual engineering materials,the mixture ratio of AC-13,AC-16 and AC-20 asphalt mixture is determined by Marshall test,and then the test specimens are formed by rotating compaction instrument.(2)Considering single axis vertical dynamic load,under the condition of different temperature and loading frequency,to carry out the dynamic modulus of asphalt mixture experiment,and then analysis of loading frequency and temperature effect on dynamic modulus.(3)With horizontal direct shear dynamic load,under the condition of different temperature and loading frequency,to carry out the shearing dynamic modulus of asphalt mixture experiment,and analyze the influence of loading frequency and temperature on the dynamic shear modulus(4)Carrying out dynamic modulus of asphalt mixture experiment on bidirectional stress state with the combination of vertical and horizontal direct shear dynamic load under the condition of different temperature and loading frequency.Compared withunidirectional loading results,vertical dynamic modulus value under bidirectional stress state are much smaller however the horizontal shear modulus test value increases rapidly,which indicates that joining a large part of vertical load can weaken the influence of shear force.