Experimental study on the determination of small strain-shear modulus of loess soil

Abstract

The primary aim of this study was to investigate the collapse potential of loess soil in Egypt, the factors affecting the dynamic properties of this soil and establish relationships between them. Whether engineered or natural, may exist in seismic zones; or may be subjected to small strain vibrations, therefore, there is a need to assess the wetting dynamic properties of collapsible soils.A series of oedoemeter and resonant column tests were conducted to study the effect of applied pressure, void ratio, water content and silt content on the collapse potential (Cp), maximum shear modulus (Gmax) and damping ratio (DT) of the tested samples. The results indicate significant increase in the collapse potential and reduction in (Gmax) with the increase of silt content. The results, also, indicate that the (Cp) is less for sample with higher initial relative densities and initial water content.Test results also show that (Gmax) increases with the increase of confining pressure and relative density. The change in damping properties is not significant under the effect of silt content and water content, and it reduces slightly with the increase of confining pressure and relative density. Empirical equations based on the results of the experimental work were proposed to predict (Gmax) with respect to (Cp), voids ratio and applied pressure.