Liquefaction Behavior of Clean Sand for Various Sample Sizes Using Triaxial Tests

Abstract

A total of 54 isotropically consolidated un-drained triaxial compression tests on various sample sizes were conducted to study the effect of sample size on liquefaction behavior of clean sand. Specimens were prepared using moist placement and dry deposition methods with different initial relative densities and tested for different confining pressures. It was observed that as the sample size increases, deviator stress also increases. Peak value of deviator stress increased as the confining pressure and relative density increased for all sample sizes for moist placement method. After reaching peak, deviator stress remained constant for large percentage of axial strain for smaller sample size, while larger-size sample offered maximum resistance to liquefaction. However, for dry deposition method opposite trend was observed especially for smaller sample sizes. Unstable zone already established by authors has been studied for all sample sizes with these two sample preparation methods. The ratio of excess pore pressure to mean effective stress at the maximum pore pressure point has been defined. The threshold value of this ratio has been found to indicate the transition from contractive to dilative behavior.

Keywords: Clean sand, triaxial compression, sample size, liquefaction, unstable zone, un-drained testing