Theory Of Strength Is Applied For Constitutive Model Of Frozen Soil

This paper discusses and analyses between theory of strength and strength and deformation laws of frozen soils under action of confining pressures, and acorrding to micro- and submicro-tests of frozen soils, the paper probes into and analyses mechanisms of strength decrease and creep of frozen soils. Through study, the following results are obtained:1. Unified Strength Theory is used in this paper through comparing, analysis a large of theory of strengths using and integrate strength and deformation laws of frozen soils. Unified Strength Theory possesses of definitely meaning and reflects property of serious materials also. That can reflect fully all of stresses on the double-shearing stress units what have different effects on damaged or yield materials. That can reflect accurately the midst-main stress effects, and can adapt flexibly to different materials in different degrees.2. As the confining pressure was increased, the strength of the frozen soil increases to a maximum value and then decreases with the continuous increase in the confining pressures. 1n other words, the increase of confining pressure can suppress as well as induce the effect of dilatancy softening of frozen soil. The change process between the confining pressures and the strength shows the parabolic pattern. Based on test results, the parabolic yield criterion was established.3. Under the action of high confining pressures, the main reasons for the decrease in the strength of frozen fine sand are: pressure melting of pore ice, particle-size breakdown and the growth of microcracks; for frozen silty clay, they are: pressure melting of pore ice and the growth of microeracks. These processes can not exist alone, but act in concert causing the decrease in the strength of frozen soils.4. The characteristics of deformation in frozen clayey soils are that the volume of specimens in frozen clayey soils contracted at initial stage of loading, but as the load was increased, the volume contracted to a certain value and then expanded with the continuous increase in the load, and the axial strain increased with the increase of deviatoric stress. The quasi-elastic, yielding and viscoplastic paxt in stress-strain curves just corresponded to the contracted part of volume, the maximum position of contracted part and the expanded part of volume, respectively. Cinder the same confining decreases pressure, with the increase of negative the axial strain and the amount of volume contraction increases;Under the same...