Assessment of internal stability of granular soils by means of theoretical and laboratory methods

The assessment of the internal stability of a base soil is a fundamental aspect in the design of the filtering transitions. It can be evaluated by means of semi-empirical, theoretical and experimental methods; the assessment of internal stability of a soil using the available semi-empirical criteria can provide different results. In the paper, in order to verify and validate two methods recently proposed by the authors (Moraci et al. 2012a, b; Moraci et al. 2015), the internal stability of granular soils using different methods is evaluated. The internal stability of test soils has been firstly obtained by Kezdi, Sherard and Kenney and Lau criteria (semi-empirical methods), then it has been assessed theoretically by the method “SimulFiltr” and finally it has been verified by long term filtration tests performed in a rigid wall permeameter. The obtained results allowed us to better define the zones that constitute the new graphical method “Butterfly Wings Chart”, recently proposed by the authors