Laboratory Investigation on the Saturation and Initial Structure Effects on the Undrained Behavior of Granular Soil Under Static Loading

The effects of the initial state of the samples and the saturation evaluated in terms of Skempton's pore pressure B on the behavior of Chlef sand were studied in this article. For this purpose, the results of two series of undrained monotonic compression tests on medium dense sand (RD= 50%) are presented. In the first test series, the influence of the specimens' fabric and confining pressure is studied. Triaxial specimens containing Chief sand with 0.5% non plastic silt content were isotropically consolidated to 50 kPa, 100 kPa and 200 kPa. The specimens were formed using both dry funnel pluviation and wet deposition. The results indicate that the confining pressure and the method of sample preparation have a significant influence on the liquefaction resistance of the sand. In the second series of tests, the saturation influence on the resistance to the sand liquefaction is realized on samples at an effective stress of 100 kPa for Skempton's pore pressure coefficient varying between 32% and 90%. It was found that an increase in the Skempton' S pore pressure coefficient B reduces the soil dilatancy and amplifies the phase of contractancy.