Based　on　the　isotropic　compression　law　of　soil,　the　total　deformation　of　soil　is　divided　into　instantaneous　and　time　delayed.　Referring　to　the　calculation　methods　for　instantaneous　and　delayed　compression　of　united　hardening(UH)　model,　an　one-dimensional　elastic-viscous-plastic(EVP)　constitutive　model　is　developed.　On　the　basis　of　an　elastic　plastic(EP)　constitutive　model　for　soil　considering　the　stress　paths　dependency,　influences　of　over　consolidated　ratio(OCR)　and　shear　stress　ratio　on　instant　compression　are　considered;the　delayed　compression　law　under　isotropic　condition　is　extended　to　three-dimensional　stress　state　by　combining　with　overstress　theory　and　plastic　potential　function　of　the　modified　Cam-clay　model.　Then　a　calculation　method　for　instant　and　delayed　compression　under　three　dimensional　stress　state　is　proposed,　meanwhile　a　3D　EVP　model　is　built.　The　new　model　contains　7　material　parameters,　physical　significances　and　determination　of　parameters　have　been　analyzed　and　given.　Comparisons　between　model　predictions　and　experimental　results　show　the　3D　model　can　describe　viscosity　properties　of　clay　and　sand　reasonably　under　not　only　conventional　stress　path,　but　also　typical　stress　paths　of　stress　ratio　loading　under　excavation.　©　2018,　Science　Press.　All　right　reserved.