In　this　study,　triaxial　cyclic　loading　and　unloading　compression　tests　were　performed　on　concrete　specimens　under　six　confining　pressures　(0,　5,　10,　20,　30,　and　40　MPa).　The　elastic　modulus　was　reduced　to　characterize　the　damage,　and　the　damage-plastic　strain　relationships　under　different　confining　pressures　were　determined.　The　results　showed　that　the　damage　evolution　rate　declined　significantly　as　the　confining　pressure　increased.　The　experimental　results　of　the　uniaxial-tension　cyclic　loading　and　unloading　tests　were　combined　to　derive　a　damage　evolution　equation　that　reflected　the　hydrostatic　pressure　effect,　and　the　material　parameters　were　determined　by　using　experimental　data.　Finally,　the　derived　damage　evolution　equation　was　embedded　into　the　Holmquist-Johnson-Cook　model　and　applied　to　numerical　simulations　of　a　concrete　slab　under　projectile　impact.　The　results　indicated　that　the　modified　Holmquist-Johnson-Cook　model　can　accurately　explain　the　damage　evolution　process　of　a　concrete　slab　under　projectile　impact.　Thus,　the　proposed　equation　can　describe　the　damage　evolution　processes　of　concrete　slabs　under　both　impact　compression　and　tension.