Load And Temperature On The Asphalt Pavement Top-Down Cracking Of Finite Element Analysis

Aiming at Top-Down cracking of the asphalt pavement and combining with material characteristics of road building material and actual observation data, the article set up 2D finite element model to analysis the mechanical response and temperature flied of the asphalt pavement. Promulgates the reasons and influencing factor of the Top-Down cracking,and discusses the measures in prevention and cure Top-Down cracks.Takes asphalt pavement transverse section as the research object.firstly,according to hard tyres wall force transmission mechanism and tyres actual load and tire pressure,building vertical and horizontal contact stress,combining damping characteristics of roadbuilding material,using finite element software ABAQUS,the article model explicit dynamic analysis.Calculation and analysis shows:Top-Down cracking due to the shear stress of the struture surface;Slow speed produces higher shear stress,which is one of the external reasones;In the same speed,material with higher damping ratio produces lower shear stress,which is one of the pathogenesis;With the mathematical statitics method analyze different factors and influence significance of Top-Down carcking in dynamic load conditions.Then, considering three cracks with different length base on existing finite element model, combining with actual observation of the different temperature condition of asphalt mixture dynamic modulus, research crack development rule under dynamic loading. Calculation and analysis shows: As the speed reduces, the shearing type stress intensity factor KⅡincreases,which means:lower speed can accelerate cracking;As the temperature increases,the apshalt dymanic modulus reduce,the shearing type stress intensity factor KⅡgoes lower;the shearing type stress intensity factor KⅡincreases as initial crack length;Over all,under the same condition pavement with simi-rigid base has can reduce the shearing type stress intensity factor KⅡ,which reflects more evident on the condition of with long crack and low temperture;and analyse Top-Down crack fatigue life by Paris expression in different condition.At last,researches temperature field and mechanical respond of the structure in three different temperture drop range.Calculation and analysis shows:after repeated actions,pavement with microcracks can cause Top-Down cracking under rapid temperture drop.In the process,tensile stress and rangeability at surface is the highest in pavement,they reduce with the depthe increased.The longer the initial crack,the bigger the tension type stress intenstity factor KⅠin the temperture drop process;When the temperture drop range increase,tension type stress intenstity factor K_Ⅰalso increase rapidly,Top-Down cracks development will be accelerated.