INVESTIGATION OF SANDY SOIL DYNAMIC STRENGTH BY THE METHOD OF SELF-EXCITED VIBRATION

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7105-99-5 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 12, 485-490 pp, DOI: 10.5593/sgem2017/12/S02.062

ABSTRACT

This paper presents a new approach to the evaluation of dynamic soil strength based on the hypothesis of discreteness of the deformation process - a method of self-excited vibration. This method was first discovered at the sandy soil shear test.
The destruction of the soil is viewed as cyclical and consists of two phases: the static and dynamic. On static stage deformation is slow, with energy accumulation. In the dynamic there is a rapid discharge, accompanied by a sharp increase in strain.
Self-excited vibrations (which can be named auto oscillation) are caused by the fact that the soil accumulates potential energy only up to a certain limit, which depends on its density, and then there is the destruction of soil structure, the instantaneous relaxation of shear resistance and plastic deformation slip. Thereafter, under the influence of an external load soil again accumulates energy gradually, and then being unloaded.
Strength parameters (angle of sliding friction φf, the angle of gearing φс and soil’s fractions connection Zw) defined at each stage, take into account the kinetics of the process of destruction and are proposed as dynamic soil strength parameters.

Keywords: sandy soil, dynamic, deformation discreteness, self-excited vibration