SANDY SOILS DYNAMIC STRENGTH PARAMETERS ACCORDING TO TRIAXIAL TESTS

Abstract

Correct determination of strength properties is always relevant for the prediction of the mechanical behavior of soils and their massifs. Under static loading conditions, the issue is prominent in domestic and foreign literature, but the determination of strength properties under dynamic loading causes theoretical and methodical issues. All developed types of tests, to date, describe particular cases of the reaction of a soil foundation under dynamic loading, a general scientific approach of determination of soil strength parameters in dynamic conditions has not been developed. The article describes the features of determining the strength and strength parameters of sand in static and dynamic conditions in triaxial tests. A review of current views on this topic is provided. On the basis of triaxial tests the method of determining the phase transformation point and the failure point is described. On the basis of the Coulomb-Mohr's strength theory and the critical state approach the strength parameters are determined. The test results concluded that the destruction of sand under both static and dynamic conditions occurs with the same ratio of normal, shearing and mean effective stresses and is described by a single critical state line (CSL), presented in the form of a bilinear equation. It has been experimentally proved that the strength of sand under static and dynamic conditions is different, the strength parameters are the same, that’s why the angle of internal friction (φ) and cohesion (C) of sand can be determined only under static conditions. At the same time to quantify the strength of soil, to assess the possibility of destruction of the soil requires a correct assessment of pore pressure, which implies conducting dynamic tests or modeling its accumulation.