A quantitative method of describing grain size distribution of soils and some examples for its applications

The grain size distribution of soils is known to be an important parameter in providing initial understanding for the physical and mechanical behavior of soils in many engineering geology applications. Therefore, the literature contains many grain size-based approaches, indices, or empirical models to describe soil for classification purposes or predict soil behavior under static and/or dynamic loading conditions. Because of the absence at present of a convenient single parameter that defines an entire grain size distribution curve, mean, median, standard deviation, the coefficients of uniformity and curvature, fines content, effective particle size etc., are currently used to describe the general slope and shape of the grain size distribution curve in engineering geological studies. In order to overcome with this limitation, comprehensive research has been performed in which an appropriate new parameter to represent grain size distribution curves is defined. Accordingly “grain size index (I _GS)” is then used in a soil classification system and empirical models to predict physical and mechanical properties of soils. Statistical analyses were performed to prove its validity and to test its applicability for prediction of soil physical and mechanical properties. In addition to the availability of the I _GS for soil classification and preliminary assessment of liquefaction properties of soil, it can also be used to estimate the swelling characteristics of expansive soils.