Undrained monotonic and cyclic response of sand–silt mixtures

Abstract

Behavior of sand–silt mixture under cyclic loading and static loading has been studied. In cyclic triaxial test, specimens were prepared by moist-tamping method, and in static test both moist-tamping and air-pluviation methods were used to prepare the soil specimens. For the sand and the non-plastic silt, the Threshold Fines Content (Fth) and Limiting Fines Content (LFC) were found to be equal at 30% of this studied sand and silt. In moist-tamping method, it was observed that the Cyclic Resistance Ratio (CRR) and Static Shear Strength (SSS) decreased with increasing non-plastic silt content till LFC; later, it remained near about constant till the time when the specimen was pure silt at constant relative density. However, in air-pluviation method, there was a peak SSS at 5% silt content; later, the value decreased with increasing silt content till LFC, and thereafter it remained constant till the specimen was pure silt. All specimens prepared by air-pluviation method showed higher SSS than those prepared by moist-tamping method except clean sand. The concept of equivalent granular void ratio was found to be more appropriate to explain the behavior of sand–silt mixtures than that of relative density and global void ratio. In both moist-tamping and air-pluviation methods, the coefficient of permeability decreased with increasing non-plastic silt content till LFC; later, it remained near about constant till the specimen was pure silt.