STUDY OF SHEAR BEHAVIOUR OF YAMUNA SAND BLENDED WITH SOFT SOIL

Abstract

The structure resulting 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 the present study, shear behaviour of virgin Yamuna sand and Yamuna sand blended with two clays of different mineralogy i.e. bentonite and kaolinite was investigated by Direct Shear test and Unconsolidated Undrained Triaxial test. Index properties and compaction characteristics of soil is also studied in this project. It was aimed to observe the shear behaviour of sand-bentonite and sand-kaolinite mixtures. Various tests conducted on virgin soil were performed for the determination of following parameters: field moisture content, Atterberg Limits, Grain Size Analysis, Standard Proctor Compaction test, Direct Shear and Triaxial Unconsolidated Undrained test. Compaction tests were conducted on mixtures of 5%,10%,15%,20% by weight bentonite and kaolinite. Direct Shear test and UU Triaxial tests were performed on mixes with 5%,10%,15%,20% by weight of bentonite and kaolinite. It was found that there is increase in MDD and OMC of the soil mixes for both kaolinite and bentonite. Maximum MDD was achieved with kaolinite clay and maximum OMC with bentonite clay. Direct shear test resulted in the increase in cohesion and decrease in friction angle for both bentonite and kaolinite. Similar results are obtained in UU Triaxial tests. However, shear parameters obtained in Direct Shear test is slightly more than obtained in Triaxial tests.