Triaxial Dynamic Mechanical Behavior of Hydraulic Asphalt Concrete: Effects of Strain Rate and Confining Pressure

Investigating the triaxial dynamic mechanical behavior of hydraulic asphalt concrete (HAC) plays a critical role in ensuring the safety of dams. Currently, there is a gap in the knowledge of its dynamic mechanical behavior under triaxial stress states and strain rates. This study experimentally examined how strain rate and confining pressure influence HAC’s dynamic mechanical behavior, focusing on failure modes, deviatoric stress–strain relationships, elastic modulus, compressive strength, and octahedral stress. The results indicated that increasing confining pressure altered the failure mode, enhanced compressive strength, and increased the elastic modulus, although it weakened the strain rate’s impact on compressive strength. HAC exhibited a pronounced sensitivity to strain rates; at elevated strain rates, specimens had greater damage, higher compressive strength (up to a 12.4-fold increase), and a larger elastic modulus (up to a 66-fold increase). Based on these findings, an empirical formula for the dynamic increase factor (DIF) was proposed, and a dynamic strength criterion was established. Pearson’s correlation coefficient analysis showed that strain rate had a more substantial impact on the HAC specimens’ dynamic mechanical behavior than confining pressure. This research provides a valuable reference for evaluating the safety of asphalt-core embankment dams.