Novel Oblique Shear Test Method and Quantitative Evaluation of Fatigue Shear Resistance between Asphalt Pavement Layers under Comprehensive Pavement Working Conditions

To quantify the impact of pavement working conditions on the interlayer fatigue shear resistance of asphalt pavement, this study independently developed a wide-angle oblique shear device. Incorporating the results of coupled moving load simulations in ABAQUS, the pavement working conditions were translated into oblique shear test parameters, and the interlayer fatigue shear resistance under different working conditions was tested and quantitatively analyzed. The main conclusions are as follows: A mapping equation was constructed between pavement working conditions and indoor shear test parameters, enabling the quantitative conversion between working conditions and test parameters; at the same temperature, an increase in axle load (0.25→0.7 MPa) resulted in a decrease in interlayer shear fatigue life (Nf) by more than 85%, while a reduction in driving speed (45→8 km/h) led to a decrease in Nf by more than 90%; an increase in road longitudinal slope (0→9%) caused a decrease in interlayer shear fatigue life (Nf) by only 25%; an increase in driving acceleration (0.0→0.6 G) resulted in a decrease in fatigue life (Nf) by 84% to 95%; and, under extreme working conditions (50°C, 0.7 MPa, 21 km/h, 0.3 G), the average interlayer shear fatigue life was less than 25,000 cycles, a reduction of more than 99%. In sections with high temperatures, low speeds, heavy loads, and frequent vehicle acceleration and deceleration (such as bus stops, intersections, tunnel entrances and exits, curves, and steep slopes), it is crucial to reinforce the interlayer bonding. The research findings can provide reference literature for the quantitative analysis of interlayer fatigue shear resistance under complex working conditions and for determining the necessity of interlayer reinforcement treatment.