Shear Fatigue Cracking Analysis of Pavement with Thick Asphalt Layers Induced by Traffic Load

Top-Down cracking is one of the major distresses induced by traffic load for the pavement with thick asphalt layers. In this paper, an analytic model of pavement with thick asphalt layers is established in which four types of base layers are considered corresponding to the different combinations of semi-rigid and granular materials. The shear stress intensity induced by the traffic load in thick asphalt layer is calculated by the analytic model firstly. Then many beam specimens of asphalt mixture are made in laboratory and the shear fatigue test were conducted. According to the test results, the fatigue cracking parameters in Paris equation were regressed. Finally, the shear fatigue life of thick asphalt layers was evaluated basing on shear stress intensity and Paris Law. The research results show that the shear fatigue life increases with the increasing of asphalt layers thickness. The structure I (thick asphalt layer with semi-rigid base and semi-rigid subbase) has the longest fatigue life and structure IV (thick asphalt layer with granular base and granular subbase) is weakest in resisting shear fatigue cracking.