Thedegradationstrengthofsoilsundercyclicloadingisstudiedandamethodfordeter-miningthecyclicdegradationstrengthwithcyclictriaxialtestsisgiveninthepaper.Furthermore,adum-mystaticmethodforestimatingtheundrainedbearingcapacityforoffshoresoftfoundationunderwaveloadsisdeveloped.Itcanconsidertheeffectofthedifferenceofcyclicstressfordifferentpartsofthefoun-dationonboththedegradationstrengthofthefoundationsoilandthebearingcapacitysothattheesti-matedresultcanbetterreflecttherealconditionoffoundationundercyclicloading.Themethodcanbeap-pliedtoplaneandspaceproblem.
