Experimental Study and Mechanism Analysis on Compression–Shear Behavior of Hydraulic Asphalt Concrete at Different Temperatures

Hydraulic asphalt concrete (HAC), typically employed as an impermeable structure in embankment dams, is increasingly recognized for its widespread engineering applications. However, investigations of the mechanical performance of HAC under combined compressive–shear stress remain limited, particularly given its temperature sensitivity. Therefore, this study investigates the mechanical behaviors of HAC under combined compressive–shear stress at diverse temperatures and normal compressive stresses. Specifically, the failure modes, stress–strain curves, peak shear stress, and strain of HAC under various temperatures and normal compressive stresses are obtained for analysis. Experimental results demonstrate that the combination of normal compressive stress and temperature induces changes in peak shear stress and correlated shear strain. Increased normal compressive stress results in vertical restriction and the emergence of horizontal cracks, with deformation amplifying at elevated temperatures. All failure modes of HAC under these conditions are absent of spalled fines and debris. It is observed that as the normal compressive stress increases, the peak shear stress progressively increases, whereas an increase in temperature yields a clear decrease in peak shear stress. The shear strength of HAC comprises the cohesion strength of the asphalt matrix and the interfacial adhesion strength between aggregates and asphalt. Finally, three modified compressive–shear failure criteria that exhibit good prediction accuracy are established for HAC at diverse temperatures. This research offers a theoretical reference for the future investigation and engineering application of HAC.