TheTheGreat-WestDykewithalengthof6.7km,thelargestseawallinChina,wascompletedinJune,1994.Thispaperintroducesstructureoptionsofnibblemoundseawallonsoftfoundationandanewtypeofarmourblock-hexagonmultiholeblock(HMB)andanewmethodoftreatmentforsoftfoundationbyusingunderwaterexplosion.ConstructionpracticeofsomeprojectsinChinashowsthatbyusingthismethodgoodeffectoftreatmentandmarkedeconomicbenefitcanbeachievedbyusingthismethod.