STUDY OF SHEAR BEHAVIOUR OF SAND BLENDED WITH SILT.

Abstract

The structure derived from compacting the soil at different water contents and energy levels can have a substantial effect on its shear strength. While the shear strength can be estimated based on the saturated shear strength parameters and the unsaturated angle of shearing resistance, limited studies have explored the variation of shear strength properties with different compaction states. In this project report, the shear strength of a sandy soil was investigated using a conventional direct shear box and triaxial test (CU) with three different normal pressures. In this project, it was aimed to observe shear strength behavior of sand blended with various percentage of silt. Three series of experiments were performed. In all series, behavior of shear strength under different testing conditions was investigated against increasing fine materials in the mixtures. Silt is used as fine material. Shear strength parameters, failure strains, stress-strain behaviors were studied. The changes in basic characteristics such as particle size distributions, consistency limits and index properties were also studied. In this investigation laboratory study on Sand (SP) blended with Silt (ML) has been carried out. Various test conducted on sand and silt were performed for the determination of following parameters: Field moisture content, Atterberg’s Limits, Grain Size Analysis, Standard Proctor’s Compaction test, Direct Shear and Triaxial Consolidated Undrained test on varying percentages of silt (by weight of 5%,10%,15%). These primary conclusions were obtained from this investigation. With the addition of silt there was considerable decrease in the value of angle of internal resistance and small increase in cohesion in the soil. During the design of structure, most of the cases the plain strain problem is carried out. Therefore an attempt has been carried out to establish a relation between the angle of shearing resistance obtained from Direct Shear test and Triaxial test.