Swelling Index and Matric Suction Relations for Unsaturated Soil Elasto-plastic Constitutive Model in FEM
The swelling index,a crucial parameter for soil deformation,holds significant importance in the critical state elasto-plastic constitutive model.Unlike the compressibility index,which has been extensively reported in lit-erature,the variation of the swelling index with matric suction has often been overlooked in theoretical studies of unsaturated soil constitutive models.To address this gap,oedometer tests were conducted on remolded silt speci-mens sourced from Hangzhou,China.Under suction-controlled conditions,utilizing an oedometer equipped with a GDS direct shear chamber,the experimental program comprised three tests conducted at matric suction levels of 50,100,and 200 kPa.The relationship between matric suction and the swelling index,denoted as κ(s),was estab-lished and fitted.Validation was performed by comparison with previous experimental studies.Furthermore,this κ(s)relationship was incorporated into an unsaturated soil-extended Cam-clay elasto-plastic model.An explicit inte-gration with a substepping error control algorithm was implemented within the ABAQUS finite element method(FEM)UMAT subroutine.The numerical modeling results of the silt oedometer tests,coupled with the UMAT sub-routine,exhibited high agreement with laboratory tests.
unsaturated soilmatric suctionswelling indexconstitutive modelfinite element method
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