Constitutive Description And Numerical Simulation Of Sandy Soil Based On Fuzzy Set Plasticity Theory

Through the earthquake analysis of structures and foundations,it is found that the damage caused by the failure of sandy soil accounts for a large proportion,which has attracted the attention of scholars all over the world.People,however,study on the deformation characteristics of sandy soil is far cannot meet the needs of the current project,it is necessary to study on the deformation mechanism of sandy soil in deep step,around the deformation characteristics of sandy soil,this paper tried to establish constitutive model can properly reflect the soil mechanics characteristics.This paper established the soil constitutive model,based on the fuzzy set theory of plasticity,an intuitive geometric figure by membership functions,to clear the description of the geotechnical material plastic recycle loading unloading process.This model is compared with the traditional elastoplastic constitutive model,more intuitive and easy to use.To verify the model of this paper is correct and effective,the work have been done and the main research results as follows:1?For different density experiment of sand has carried on the conventional triaxial compression test,and the test results are analyzed,the results show that the volume strain of sand on different confining pressure can produce different degree of dilatancy and cut.Shear,sand body in first shrinkage deformation,along with the increase of the external force and dilatancy.Sandy soil easier to dilatancy under low confining pressure.Loose sand is easy to cut and dense sand dilatancy easily.2?On the basis of fuzzy set theory of plasticity,established a fuzzy set plastic soil constitutive model,using the Matlab program and test of sandy soil,compares the conventional triaxial compression test results fully verified the sandy soil constitutive model established in this paper,is correct and effective.3?Using the verified plastic soil constitutive model of fuzzy sets,sandy soil is discussed in four different stress path(TE,TC,RTE,CTC)under mechanical properties.Although sand final failure pattern is similar,but different stress paths on the strength of the soil has a great influence,the strength of the soil by the passive triaxial compression(CTC)stress path,such as p compression stress path(TC),such as p when the tensile stress path(TE),and the active compression stress path(RTE)decreasing,and the triaxial compression test(RTE)stress path actively intensity of the peak intensity of the passive triaxial compression test(CTC)stress path reduces about 70%.Different stress path on the deformation of the soil has great influence.For the same initial condition of sandy soil in triaxial test,the dilatancy property according to the stress path of RTE,TE,TC and CTC in turn reduce,the same partial strain corresponding body strain numerical reduce in turn.For the same kind of sandy soil in the triaxial tensile test of dilatancy sex ratio in the triaxial compression test showed the dilatancy of sex is much smaller,sometimes even no dilatancy.4?By comparing with the test results,the sandy soil slants deviatoric stress-strain relationship curve,the volume strain-stress-strain relationship curve,and average volume strain curve fitting results of the ideal,can be thought of in this paper,the established based on fuzzy set theory of plasticity of soil constitutive model can well describe the mechanical properties of soil,further verify the correctness and validity of the model.5.Finally,the paper expounds the main conclusions of this paper are also presented according to the conclusion.