Comparative Study Of Different Strength Criteria And Different Constitutive Models

The strength and deformation characteristics of geotechnical materials are important research contents in geotechnical mechanics.In order to promote the further development of constitutive model theory,this paper mainly studies and analyzes from the following aspects.(1)This paper introduces the basic principles of Mohr Coulomb strength criterion,Drucker Prager strength criterion and Hoek Brown strength criterion,and summarizes the application scope and application conditions of the three strength criteria.Among them,Mohr Coulomb strength criterion does not consider the influence of intermediate principal stress,and its calculation results are relatively conservative;Drucker Prager strength criterion considers the influence of hydrostatic pressure and intermediate principal stress,but its calculation results are relatively dangerous;Hoek Brown strength criterion is an empirical strength criterion reflecting the nonlinear failure of rock mass,but its parameters are difficult to be accurate The determination of the quality of the products.(2)A new constitutive model is introduced,and the basic equations,parameter determination,correlation coefficient and the new model characteristics constitutive model are introduced in detail.The new constitutive model includes two forms: shear stress-strain and principal stress-strain.This model can not only describe a variety of mechanical behavior characteristics,but also explain the discontinuity of stress and strain in the post failure zone of rock and soil.It provides a new attempt to establish a unified geotechnical theoretical model.(3)This paper systematically introduces a three-dimensional unified hardening softening constitutive model of concrete.The parameters in the model can be calculated by experiments and related formulas,and also have clear physical meaning.It can be applied to different types of concrete materials,and can reasonably describe the deformation and strength characteristics of concrete materials.(4)Taking a concrete triaxial test as an example,firstly,the new constitutive model is compared with the stress-strain relationship under the above three strength criteria.The research shows that the new constitutive model can simulate the stress-strain relationship of the concrete material under the three strength criteria,which verifies the applicability of the new constitutive model It can be seen that Drucker Prager strength criterion has the highest correlation coefficient,which indicates that the new constitutive model has the best fitting degree under Drucker Prager strength criterion.(5)A three-dimensional unified hardening softening constitutive model of concrete is used to calculate the concrete case and simulate the stress-strain curve,and the results are compared with the simulation results of the new constitutive model under Drucker Prager strength criterion.The results of the two constitutive models are satisfactory,but the new constitutive model has a higher fitting degree of stress-strain curve in the post failure region,which can better reflect the mechanical characteristics of concrete materials in the post failure region under complex stress.