DETERMINATION OF NONLINEAR STRENGTH CHARACTERISTICS OF SANDY SOIL BASED ON THE GRIGORYAN SOIL MODEL
Verification of nonlinear functional dependences of the Grigoryan soft soil medium model that characterize the soil resistance to shear deformation - i.e., the dependences of the yield strength on pressure and the shear modulus on density, is carried out. The equations of the Grigoryan soil environment model are modified to account for the variability of the shear modulus. An example of numerical implementation of the obtained equations in Lagrange variables based on the technology of integrating user material into the dynamic strength module of the LOGOS software package is given.An analytical solution is obtained that represents the loading path in the element of the ground medium on the plane of the main stresses during loading and unloading under uniaxial deformation. The linear dependence of the yield strength on pressure and the linear dependence of the shear modulus on density were assumed. It was assumed that the volume compressibility curves for loading and unloading are known. Calculations are performed and a good correspondence between the results of numerical calculations and the analytical solution is shown. Calculations are performed showing the influence of the parameters of the pressure-dependent yield strength and the density-dependent shear modulus on the loading curve on the plane of the main stresses.The parameters of nonlinear functional dependences of the Grigoryan model of the soil environment are determined on the example of known experimental data on the deformation of a sample of dry sandy soil in a bounding cage using The Hopkinson split rod system and the Kolsky method. A fractional-rational dependence of the yield strength on pressure and a bilinear dependence of the shear modulus on density were assumed. It is shown that the use of linear dependencies allows us to obtain a correspondence of the calculation results with experimental data only in special cases with the appropriate selection of parameters. The use of a nonlinear dependence of the yield strength on pressure with a single set of parameters provides a good agreement with the experimental data of various authors for stresses up to 125 MPa.