Factors Influencing the Behavior of Rockfill Materials

Abstract

In the present experimental work, quarried rockfill material from a Lift Irrigation Project, India has been considered. The largest size of particle (dmax) of the prototype gradation rockfill material is 600 mm. Such a large size rockfill material is not possible to test in the laboratory. Hence, for laboratory testing, modeled technique is used to scale down dmax up to a maximum size of 25, 50 and 80 mm. Engineering behavior i.e., stress, strain and volume change characteristic of scale downed material is considered and presented in this paper. Stress–strain behavior of the tested rockfill material has been found hyperbolic in nature, inelastic and stress dependent. The axial strain and the deviator stress increase with increase in confining pressure for all the dmax. From the axial strain–volumetric strain characteristic, it is observed that the material compresses/is contractive in nature in the initial portion of the curve and experiences dilation on further loading. The effect of dilation however diminishes with rising confining pressure and dmax. The parameters of shear strength, i.e., angle of internal friction, ϕ for all the dmax, are determined. Frictional angle, ϕ of the tested quarried rockfill material, decreases with increase in dmax. Also, it is observed that the shear strength parameter (ϕ) decreases with increase in confining pressure. Therefore, the study shows that the maximum size of particles and cell pressure affects the frictional angle (ϕ) of the tested quarried rockfill material.