Characterizing the process of liquefaction initiation in Anzali shore sand through critical state soil mechanics

A series of monotonic drained and cyclic undrained triaxial tests were conducted to study the cyclic behavior of a shore sand mainly formed of silica and carbonate, under critical state soil mechanics framework. The main focus of the study was on simplifying the process of approaching to liquefaction, and predicting it using the concept of "state". The results indicated that generation of pore water pressure from the start of cycling to liquefaction can be simplified into a bilinear-shaped trend in a semi-logarithmic space. The pore pressure response, the number of cycles needed for liquefaction and the cyclic resistance ratio were shown to depend on the initial state relative to the critical state line in space of specific volume against logarithm of mean effective stress. Analysis of the results also indicated that the bilinear trend of approaching to liquefaction and the liquefaction resistance of the soil with various densities and stress levels could be well characterized in terms of the state parameter and the cyclic stress ratio, using logarithmic, exponential and quadratic formulations. Liquefaction curves were derived in terms of the state parameter, independent of soil density and stress level. (C) 2015 Elsevier Ltd. All rights reserved.