Mechanical Behaviours of Typical Asphalt Pavement Structures under Wheel Loads

The mechanical behaviours of three typical asphalt pavements including semi-rigid base, inverted and composite asphalt pavement under wheel loads were analyzed and compared based on the tests on the asphalt pavement test section constructed in Chengdu-Deyang-Nanchong expressway. Comparing with static deflection of pavement surface obtained by Beckman beam test , static analysis based on elastic multi-layered theory was carried out. Pre-plugged asphalt strain gauges were used for the three asphalt pavement test section to measure in-situ dynamic responses caused by moving vehicle with different axle loads or at different speeds. The results show that fatigue cracking is more likely to appear in the transverse direction of asphalt pavement. The peak values of tensile strain in the vehicle traveling direction and the transverse direction of bottom of inverted asphalt surface are respectively 1.24 and 1.30 times those of composite asphalt pavement, and 2.37 and 2.67 times those of semi-rigid base asphalt pavement respectively.For pavement structures of the same thickness, semi-rigid base asphalt pavement has great advantage in decreasing fatigue cracking of asphalt surface and permanent deformation, and the force bearing capacity of the composite asphalt pavement is close that of the semi-rigid base asphalt pavement, which thus can be replaced by the composite asphalt pavement partially. Although the inverted asphalt pavement is less sensitive to axle load than other pavement structures, the thickness of its asphalt surface or asphalt treated base should be increased appropriately to improve force bearing capacity, and moreover the tensile stress of the asphalt treated base should be controlled strictly to decrease the fatigue damage of the inverted and composite asphalt pavements.