The　offshore　wind　turbines　(OWT)　are　subjected　to　cyclic　loads,　such　as　ocean　waves　and　wind,　over　extended　periods.　The　soil　surrounding　the　pile　experiences　bi-directional　cyclic　shear.　As　a　result　of　the　low-frequency　and　long-term　loading　in　the　pile-soil　interaction,　the　cumulative　deformation　of　pile　foundation　increases,　posing　a　risk　to　the　operational　safety　of　wind　turbine　system.　The　soil　around　the　piles　is　distributed　with　soft　clay　and　clay　layers.　To　study　the　cumulative　deformation　properties　of　clay　under　complex　stress　states.　A　series　of　tests　are　conducted,　the　variation　of　resilient　modulus　under　different　cyclic　stress　levels　and　confining　pressures　is　analyzed　based　on　test　results.　Then　an　empirical　model　uniformly　reflecting　strain-hardening　and　strainsoftening　properties　of　clay　is　proposed.　The　variations　of　model　parameters　are　investigated.　Then　the　established　empirical　model　is　used　to　modify　the　maximum　elastoplastic　modulus　at　each　unloading　within　the　bounding　surface　constitutive　model,　a　parameter　reflecting　the　magnitude　and　rate　of　strain　accumulation　is　also　introduced.　This　method　is　characterized　by　a　simple　expression　and　requires　fewer　model　parameters.　Finally,　the　predicted　results　of　modified　constitutive　model　are　compared　with　test　results　to　verify　the　validity　of　the　established　model.