Study On Estimation For Fatigue Cracked Life Of Asphalt Pavement Based On Local Strain

Continuously developing with the communication cause,asphalt pavement has been the main structure form in China's high grade pavement,of which semid-rigid basepavement account for more than 90%. Because of large traffics and seriously overloading,the poor-fatigue performance has been completely exposed and it can't meet the requiremts.As a result,durable pavement with better performance and longer life has been studied at home and abroad.Rigid pavement is a kind of durable pavement.It has higher strength and stiffness,better integrity and stability,good scouring resistance and cracking resistance,and can provide abiding basic condition and holding power. The most critical technical problem is preventing reflection crack.Therefore,it is necessary to study faigue cracking in asphalt pavement.This paper puts forward reasonable test conditions for direct tension test.The tests controlled with strain werecarried out on asphalt mixtures.Circular stress-strain cure equations and strain-life fatigue equations of the asphalt mixture have been established with the way of multilevel and multi-specimens.This psper also proposed the minimum and maximum of cracking tension strain of the asphalt mixture.Based on the local-strain theory,the local strain of asphalt pavement can be caculated by Kt—Neuber equation and Kf—Neuber equation. Converse loadings to true strains at the bottom of asphalt surface where stress concentrated.Fatigue cracking life can be predicted By the combination of the strain-life fatigue equation measured by tests and local strain by caculation.