A　constitutive　model　of　methane　hydrate-bearing　sediment　(MHBS)　was　recently　proposed　based　on　a　stress　partition　framework　(SPF-MHBS).　To　capture　the　mechanical　behavior　of　MHBS　under　a　wide　range　of　effective　confining　pressures,　this　study　introduces　the　equivalent　granular　void　ratio　(e*)　and　the　particle　breakage　index　(Br)　associated　with　critical　state　variables　into　the　original　SPF-MHBS　model.　A　comprehensive　set　of　triaxial　tests　on　MHBS　under　0.2–20　MPa　effective　confining　stress　were　simulated.　The　simulation　results　indicate　that　based　on　appropriate　parameter　calibration,　the　response　of　specimens　under　low　effective　confining　stress　can　be　acceptably　represented　using　the　original　SPF-MHBS　model.　However,　at　high　confining　stress,　the　simulated　strength　of　pure　sand　was　overestimated,　while　that　of　the　hydrate-bearing　specimen　was　and　underestimated.　Dilatancy　was　also　significantly　overestimated　at　high　confining　stress.　After　introducing　the　e*　into　the　original　model,　the　performance　under　relatively　low　pressure　is　improved　and　three　model　parameters　are　reduced　from　the　original　model.　After　introduction　of　Br,　the　model　performance　is　further　improved　at　high　confining　stress.　The　improvements　allow　the　SPF-MHBS　model　to　provide　a　unified　description　of　MHBS　behavior　under　a　wide　range　of　confining　stress.　©　2023　Elsevier　Ltd