Engineering Behavior of Alluvial Rockfill Material: Fid-Bau Portal

Engineering Behavior of Alluvial Rockfill Material

Chakraborty, Uday Bhanu / Honkanadavar, N. P.

Rockfill dams are commonly being constructed to store the natural river water for using to generate the electricity, irrigation, drinking and industry etc. Rockfill material consisting of gravel, cobbles and boulders obtained either by natural riverbed and blasting the rock quarry. These materials are being used because of their inherent flexibility, capacity to absorb large seismic energy, reduce pore water pressure and adaptability to various foundation conditions. The engineering behavior of rockfill material affects due to mineral composition, particle size, shape, surface texture, confining pressure, gradation etc. Rockfill materials consist of particles of large size more than 1200 mm and this cannot be tested directly in the laboratory. Some kind of modeling technique is often used to scale down the size of particles so that the specimen prepared with smaller size particles can be tested in the laboratory. Among all modeling techniques, the parallel gradation technique is the most commonly used and the same has been used in the present study. The alluvial riverbed rockfill material is obtained from a hydropower project in Jammu & Kashmir. The maximum particle size used in the dam is 600 mm. For testing, the maximum particle size (d_max) is scaled down to 25, 50 and 80 mm by parallel gradation technique. All the d_max are tested for 87% relative density. Large size-drained triaxial tests are carried out with a specimen size of 381-mm diameter and 813-mm height with varying confining pressures from 0.6 to 1.8 MPa. Engineering behavior means stress–strain-volume change behavior of all the d_max under different confining pressures are studied and presented.