Equivalent granular void ratio and behaviour of loose sand with fines
Traditionally, void ratio is being used as a state variable for liquefaction analysis of sand with fines. However, recent publications reported that void ratio is not a good state variable for sand with fines. Thus, equivalent granular void ratio, e* instead of void ratio, e is proposed to resolve this problem. A single trend for Steady State (SS) data points for sand with fines can then be achieved in e*-log(p') space irrespective of fines contents, fc. The single trend is referred to as equivalent granular steady state line, EG-SSL. However, a parameter b, the active fraction of fines in sands force structure, is needed in the conversion to e* from e. The biggest challenge in using e* is to get physically reasonable b. There are many approaches namely assumed/back analysis, prediction etc have been seen in literature to obtain b. This paper critically examined these approaches in the light of critical state soil mechanics, CSSM framework. Then the prediction approach is used to examine the applicability of the EG-SSL as an alternative SSL irrespective of fines contents under CSSM framework. The outcome was excellent. Then the prediction approach is used to correlate other void ratio dependent soil behaviours such as cyclic resistance to liquefaction (CR), instability stress ratio (ηIS), small strain shear modulus (G) etc. Good correlations were also observed for these behaviours.