Influence of Different Stress Conditions on Behavior of Rockfill Materials

Abstract

Rockfill material is the most readily available and the most flexible material for the construction of dams especially in the seismic prone regions. The material is obtained either by blasting available rock or is collected from the alluvial deposits of the river. During construction of the dam, the available rockfill material is compacted to required density layer by layer using various sophisticated compactors to achieve the required density and slope. Gradually the vertical load on the lower layers goes on increasing due to placement of subsequent layers of the materials to achieve the desired height. This may result in variation of grain size distribution of the lower layers due to the breakage of particles. This will certainly influence the shear parameters. Present studies have been carried out to find the influence of loading the rockfill materials under two different stress conditions i.e. multistage loading and single stage loading on the grain size distribution and its subsequent effect on its shear parameters. Consolidated drained triaxial shear tests have been conducted on the materials obtained by blasting available rock as well as on the materials collected from the alluvial deposits of the river which are generally used for construction of rockfill dams. Test data have been analyzed to study the breakage factor and corresponding shear parameters under both conditions.