Experimental Investigation on Undrained Shear Behavior of Overconsolidated Sand-Silt Mixtures: Effect of Sample Reconstitution

Liquefaction stability analysis using the undrained shear strength characteristics of sandy soils that are prone to liquefaction is a major challenge in geotechnical earthquake engineering. The objective of this laboratory research work was to study the combined effect of the sample reconstitution (dry funnel pluviation and wet deposition) and overconsolidation ratio (OCR = 1, 2, 4, and 8) on the undrained shear strength of medium dense (D_r = 52 %) sand-silt mixtures under undrained monotonic loading conditions. For this purpose, a series of triaxial tests were carried out on reconstituted saturated silty sand samples with fines content ranging from 0 to 40 %. The confining pressure was kept constant to 100 kPa in all tests. The obtained data showed that the dry funnel pluviated samples were more resistant than the wet deposited samples and complete static liquefaction of samples reconstituted with wet deposition method was observed for the lower overconsolidation ratios (OCR = 1, 2, and 4). The undrained shear strength decreases with the increase of fines content for dry funnel pluviation (DFP) and the inverse tendency was observed in the case of wet deposition (WD) for the range of the overconsolidation ratio under consideration (1 <= OCR <= 8).