The mechanical properties of hydraulic asphalt concrete (HAC) are crucial to the safety and stability of asphalt core dams. Currently

the failure mechanisms of HAC under different confining pressures haves not yet been fully understood

and the relationship between confining pressure and its deformation behavior lacks comprehensive research. And

there exists certain controversy about the determination of its anti-seepage failure point. This paper examines the effect of confining pressure on the failure mode

deformation

and compressive strength of HAC through experimental tests. The results indicate the failure mode of specimens is affected significantly by confining pressure. With an increase in confining pressure

both the peak axial strain and peak lateral strain of HAC increase

during which the former increased by 4.12 times at most

while the peak volume strain tends to be stable; The increase in compressive strength with confining pressure can be described by a power function. We suggest that the peak strength point be taken as the anti-seepage failure point of HAC

and we formulate a corresponding failure criterion. This work clarifies the relationship of the axial strain at the water-inlet point versus the axial strain at the peak-stress point

and laid a theoretical basis for determining the seepage prevention failure point.