Research On Constitutive Model Of Frozen Soil Based On Composite Mechanics

Frozen soil is a complex composite material that composed of soil skeleton,ice,non-frozen water and gas.Because it contains rheology ice, the mechanical properties have great differences compared to common soil.Since the famous works <<Frozen Soil Mechanics>>,whose auther is H.A., coming out, frozen soil mechanics has got great development.former soviet begun to study since 1930s,while north America since 1950s.China also begun to do a lot of experiments and system reaearch on the strength and creep of frozen soil since 1960s.The construction of Qinghai-Tibet railway provided new opportunities. domestic and foreign scholars build the model of frozen soil bsed on thermodynamics and mixture theory while seldom based on micromechanics.doing research on constitutive model of frozen soil has very important significance not only for Frozen Soil Mechanics enrichment and development but also for accurate prediction of frost heaving,thaw settlement and stress-strain state of frozen soil structure. That is to say, Frozen soil is regarded as composite material.This paper made a systematic exposition of the development in the study of composite materials and theoretical method. Analysis is made on the fabric characteristics of frozen soil and key technical problems. Inclusion theory is applied to research constitutive model of frozen soi,which greatly decreased test times and lay a foundation for frozen soil engineering numerical calculation.what is more, providing theoretical basis for Frozen Soil Mechanics . Mainly includes the following several aspects the content:(1) Macroscopic strength theory and micromechanics.to introduce anisotropy strength theory and interaction theories that include maximum scale stress theory,maximum strain theory,Tsai-Hill criterion,Hoffman criterion as well as Tsai-Wu stress tensor polynomial theory.then effective modulus of composite materials is estimated,solving this problem under different hypothesis can form micromechanics approximate method,points out all mature methods thoughts and applicable condition,offer help for derivation of constitutive model of frozen soil.(2) Search status and results of strength characteristic and constitutive model of frozen soil are summarized. Two methods are proposed to establish constitutive model of frozen soil, that is, inclusion theory and single-cell theory in micro-mechanics are applied to establish constitutive model of frozen soil which is regards as transversely isotropic materials, and this theory is briefly introduced and is used to establish a elastic constitutive model of froze soil, Elastic constitutive model is characterized as function of the rate of ice. Micro-mechanics of composite materials, FEM and advanced test means should be applied together to establish constitutive model of frozen soil to provide theoretical basis for engineering construction in cold regions.