Unsaturated Soil Mixture Of Theory And Its Applications

The constitutive model plays very important role in soil mechanics and related engineeringareas. The birth of new constitutive model always brings about reform and progress in many aspectsof soil mechanics. The creation of constitutive model is a complex and arduous work,and it is oneof the hottest research topics in soil mechanics. Bup, up to now there is no constitutive model whichcould fully describe the characteristics of soils.The cause this state is the lack or suitable basictheory and theoretical means. In this paper, using mixture theory, the soil was investigated assaturated mixture composed of solid, liquid and gas. Wich mixture theory's ability to solving theconstitutive problem, fundamental assumptions about unsaturated soil mixture and mathematicaldeduction,the constitutive and field equations of the unsturated porous medium(including the unsaturated soil) were constructed. Then the simplification forms and applications ofthese equations, such as the dynamic response and consolidaiton of unsaturated soil as well as thedynamic interaction of unsaturated soil and foundation, were discussed.To demonstrate the basic thought and common method of dealing with constitutive problem inmixture theory, the mixture theory of fluid and solid was developed before the constitutiverelationship of unsaturated soil was studied. The constitutive equations and field equations of themixture were formed,which included the influences of elasticity,viscosity,heat conduction,heat conduction,buoyancy and the constituent volume fractions.using the theory of mixture,the constitutive problem of unsaturated soil was fully andsystematically investigated for the first time. The framework of the mixture theory of unsaturatedsoil(generally speaking, the porous mixture of solid, liquid and gas) was constructed First, the fundamental assumptions of the mixture of unsaturated soil was proposed.Second,the entropyunequality of unsturated soil mixture was set up. Third,the nonlinear constitutive equations andfield equations were established.Fourth,these nonlinear equations were linearized, and the linearviscoelastic constitutive equations and field equations of isotropic unsaturated soil were obtained,which includes the effects of temperature gradient and constituent volume fractions. Finally,thelinear elastic equations of unsaturated soil were expressed in the form similar to the Biot's linearelastic equations of saturated porous medium, and thus the Biot's type equatoins of unsaturated soilwere formed.The established constitutive equations and field equations were simplified to several speciallaws,which describe the fundamental characteristics of soil. The main conclusions are: l) Theunsturated soil dose not have single stress state variable as the effective stress of saturated soil. Ifthe sOl's ~ nd porOUS ~ are bosnde, to bo the bes de Of areboSOil two be be variabl pe bo of od des ed PorOUS gaS poare as well as~ must be ed 2) Drv's law is suhaWe tO gOm the bo of POrere lluld ~d and gas)in unsod so' ana the -- ed- or~ ana po are ds to the ~ anasbo depe Of snil. 3) Boit's wited POrOuS theq is usds tO the bo elasti sdsson ana it is the pe orthe tw in the pe bo co-bo ed the boS ofthe the tw or ed son ~d bo. In ~ the ds ror -- theelaSbo wt Of wt sOil are Wed, aod the wi coul be pe whthe ds nd nd pe.The bo btw tw metkod tw Qf unswi sOil tw wte in bodoInain(UD is 8et uP De tw W Of W doW Wc wte forisotw linW ed -- sOil is ~. m ~ bo Of ch disP-- andpo natd peme m bo m bo soto or unar - for ffe~ ~ ~ or un was conswt ho is the bo or sare. mgh sote or bofo- on m bo ho the nd bo mechorBare is wh ds to the ~ sotaA the bo ed on consds Of arebo soil was thesked. Fnd theconsta ~ m set ny As in the are or m the pe ds or sonadisPtw and pe fiuld peare in maturated soil were ~ as the -- alloutthe LaPbo transfm of hadamehal sbo and b~ ds. m bosoheons in LaPare hobo domain were aiso -- So Ike base fOr ed BEM Of...