Constitutive Model Research Of Turfy Soil In Jiangyuan Town Dunhua City Based On Multipotiential Surface Model

This paper is based on the national natural science foundation of china, which isstructure character and constitutive model research of turfy soil in seasonal frostregion, settlement research of Jilin to Yanji highway in seasonal frost region, thedeformation and stability of road in Heda highway research region. The research isbased on outdoor survey and analysis of interior trial, get the trial data reflect the turfysoil of this region through conventional triaxial compression test, and then get theparameters applied for multipotiential surface model through Duncan-Chang model,and at last get the simulation of the turfy soil through multipotiential surface model,which provides theory support for the analysis of the turfy soil of this region.Tury soil is the quaternary period Holocene deposited soil, the formation of turfysoil is symbolize of end of ice age and climate warming, turfy soil is early age ofdeposited soil. Turfy soil is special humus compositions which is highly pore spaceratio, highly water content, and highly organic matter, and formed in swampenvironment. The constitutive model research of turfy soil is the key issue ofmechanics research of turfy soil, at present, the research of constitutive model of turfysoil is mainly based on multipotiential surface model which was divorced from yieldcondition, plastic flow rule, and hardening law. The generalized potential theory studythe decomposition of the plastic strain increment, and deduced the relationship ofstress and strain on the basis of mathematical, thus, gave up three basic assumptionswhich is yield condition, plastic flow rule, and hardening law in the process of modelfoundation.The innovation points of this paper:(1)Compared the non-linear theory, traditional elastic theory and the generalizedpotential theory from mathematics essence, and draw the conclusion: the compare ofevery theory is mainly determined by stiffness matrix. The elastic model can notreflect the dilatancy of the plant in the case of no cross terms in stiffness matrix, at the same time it is inevitable to lead the result of simulate of the model to big, throughoverlapping the relationships of every terms.(2) comparing and simplified multi-potential surface model smiling the strainincrement typical step-by-step calculation to the conclusion: Duncan-Chang modelstiffness matrix assuming equal to the cross-term, will lead to the calculation result istoo large, the fact that only a model stiffness matrix to meet the full rank and upperand lower triangular matrix elements independently of each other to make the resultsmatch the actual stress results, it is clear that the multi-potential surface model to meetthe requirements of the central authorities. Multi-potential surface model is obtaineddirectly from the experimental curve independent of the plastic coefficient, thecalculation results will be more reasonable and accurate.(3) when the peat soil constitutive model, taking into account the inherentcomplexity and regularity of peat soil, peat soil plastic strain divided into quasi-elasticpart and pure plastic part. Elastic part of the classical theory of elasticity fittinganalysis, and then give up the yield criterion, flow rule, hardening law to create theplastic part of the model, with specific engineering practice to test the applicability ofthe model.