Dynamic Behavior Analysis of Barak River Sand Using Resonant Column Apparatus

The whole of the northeast region of India lies in the seismic zone V. Barak River flows through the Silchar town of Assam. Several construction projects utilize the sand extracted from the Barak river for carrying out their operations; hence, its dynamic analysis becomes important. This study aims to experimentally investigate the dynamic behavior of Barak river sand in dry conditions by varying influencing parameters such as confining pressure and relative density, at a very low strain condition. The most important parameters in the dynamic analysis of soil include shear modulus and damping ratio, which were evaluated using resonant column apparatus in the torsional mode of vibration. The sand samples were prepared by compacting to relative densities of 30, 50, and 65% and tested at confining pressures of 50, 100, and 200 kPa. It was observed that with an increase in strain percentage, the shear modulus of the test sand decreased, but the damping ratio values increased. Shear modulus values obtained were found to be proportional to confining pressure and relative density, but the damping ratio followed an inverse trend. The outcomes of the present study can be implemented in the designing of foundations and structures exposed to dynamic loads.