Underwater　explosions　have　always　been　a　hot　topic　in　the　field　of　ship　protection.　When　explosives　explode　in　offshore　waters,　the　influence　of　seabed　and　structural　boundaries　on　shock　wave　propagation　and　bubble　pulsation　will　become　more　complicated.　In　this　paper,　a　numerical　simulation　study　of　the　underwater　explosion　between　a　deformable　seabed　and　a　rigid　boundary　is　carried　out.　Firstly,　the　ABAQUS　software　was　used　to　establish　a　numerical　model　by　using　the　CEL　method.　The　seabed　was　regarded　as　a　heavier　fluid,　and　the　density　ratio　of　the　seabed　and　water　was　used　to　describe　the　characteristics　of　the　seabed.　The　validity　of　the　model　was　verified　by　comparison　with　experiments.　Then,　a　series　of　numerical　simulations　were　carried　out　by　adjust　the　position　of　the　explosive,　the　thickness　of　water　medium　layer,　and　the　density　of　the　seabed.　The　results　show　that:　when　the　position　of　the　explosive　is　close　to　the　seabed　and　the　rigid　boundary,　the　bubble　pulsation　period　is　longer.　The　water　jet　and　the　pulsating　pressure　of　the　bubbles　have　a　strong　impact　on　the　structure　when　the　explosive　is　located　near　to　1　times　the　theoretical　maximum　radius　of　the　bubble.　As　the　depth　of　the　water　decreases,　it　can　be　observed　that　the　bubbles　transform　from　＂ellipsoid＂to　＂nipple-like＂,　and　finally　tear　into　upper　and　lower　halves.　When　the　thickness　of　water　medium　layer　is　1　times　the　theoretical　maximum　radius　of　the　bubble,　the　incident　pressure　waveforms　of　the　bubble　pulsation　and　the　water　jet　near　the　structure　are　chaotic,　which　is　caused　by　the　＂tear＂phenomenon　of　the　bubble.　As　the　density　of　the　seabed　increases,　the　depth　of　the　intrusion　of　the　bubbles　into　the　seabed　becomes　smaller　and　the　shape　of　the　bubbles　becomes　flatter.　The　research　results　of　this　paper　can　provide　reference　for　the　protection　design　of　ships.　©　Published　under　licence　by　IOP　Publishing　Ltd.