Evaluation of Internal Stability of The CEN-Standard Sand Based on Different Gradation Methods

Abstract

For granular soils to perform their filter and drainage duties healthily, their internal stability must be ensured. The internal stability of granular soils is disrupted by the suffusion/suffosion mechanism, which is defined as the movement of relatively fine materials through the voids in the soil matrix by seepage flow. In granular soils, relatively coarse material and voids remain in areas where suffusion/suffosion occurs. Due to these voids, their permeability increases, and as the velocity of seepage increases, Backward erosion (piping) may develop. Again, in areas where relatively fine materials are transported, increased pore water pressures due to clogging may disrupt the static stability of earthen structures built with such soils. For this reason, evaluating the internal stability potential of granular soils in designing engineering structures such as embankment dams used in filter design is critical. There are many methods in the literature by which the internal stability of granular soils can be evaluated through the PSD curve. This study compares and presents the results of seven evaluation methods selected from the literature using CEN Standard Sand EN 196-1 material. According to the results of this study, CEN Standard Sand TS EN 196-1 material was evaluated as internally stable according to all methods. Accordingly, this material can be used as a reference in assessing the internal stability of granular soils within their particle size range.