Research On Dynamic Strength And Constitutive Relationship For Geotechnical Materials Bases On The Triple-Shear Unified Strength Theory

In this paper, through combining triple-shear unified strength theory with soil dynamic strength limit equilibrium concept, transform the three shear unified strength criterion formula, take the decrease of cyclic strength of materials into consideration and add factor of correction of the strength reduction dynamic load strength, this paper derived the calculation formula for geotechnical materials dynamic strength. And then compared the formula calculation results with existing data from true triaxial experiment on concrete dynamic which are done by Dalian University of Technology, found that results by triple-shear unified strength theory dynamic strength calculation formula calculation has certain accuracy, and is better than the results by Mohr Coulomb criterion.On the basis of static elastic-plastic constitutive model by triple-shear unified strength theory, considering kinematic hardening, this paper derives a suitable dynamic constitutive relationship for general geotechnical materials, this constitutive relationship has a certain generality.This paper further combining boundary surface theory, deduced a dynamic constitutive model for saturated clay on CU condition by assumed that the boundary surface will not move, and the loading surface with each loading frequency change constantly changing. The model fully considers the characteristic of initial cyclic hardening and subsequent cyclic softening of soil. Furthermore there is only one loading surface and a boundary surface, so the model is very simple. This model can provide reference for derivation of dynamic constitutive model in dynamic true triaxial situation and provides theoretical basis for dynamic true triaxial test in the future.