Experimental Study on the Pore Water Pressure Generation Characteristics of Saturated Silty Sands

Abstract

The excess pore water pressure produced during earthquake shaking causes liquefaction and influences significantly the shear strength, deformation and settlement characteristics of granular soil deposits. Therefore, the stability of the structures constructed from these deposits or founded on them is adversely affected. The mechanisms of pore pressure generation and, in turn, liquefaction resistance of granular soils are still not fully clear and require further research. For the purpose of clarifying and evaluating pore pressure buildup characteristics of sandy soils, a series of undrained monotonic triaxial tests were carried out on different reconstituted samples of sand–silt mixture at various intergranular void ratios. The soil samples were tested under a constant confining pressure (\({\sigma_{3}'=100 {\rm kPa}}\)) and at three relative densities (Dr = 20, 53 and 91 %). The results obtained from this study reveal that the fraction of low plastic fines plays an important role in the generation of excess pore water pressure in samples of the Chlef sand–silt mixtures. It was found that excess pore water pressure can be correlated with the undrained shear strength at the peak for the range of fines’ content under consideration. The gross and intergranular void ratios appear as pertinent parameters to represent the pore water pressure response of the sand–silt mixtures for a given fines’ content.