International Journal of Research and Scientific Innovation (IJRSI) | Volume IV, Issue X, October 2017 | ISSN 2321–2705

Strength and Dilatancy of Granular Materials

K.V.S.B. Raju*and Nivya E.C**
* Assistant Professor, Department of Civil Engineering, University Visvesvaraya College of Engineering (U.V.C.E), Bangalore,University, Bangalore, Karnataka, India
** Formerly Post Graduate Student, University Visvesvaraya College of Engineering (U.V.C.E), Bangalore University,Bangalore, Karnataka, India

Abstract: In the present study an attempt is made to evaluate the strength and dilatancy parameters of glass beads and etched (rough) glass beads. A series of direct shear tests were performed on sample of glass beads and etched glass beads. The size of glass beads was varied from 1mm-1.7mm,1.7mm-2.36mm and 2.36mm-4.75mm and mixed together to obtain the required sample. The different relative densities at which tests were conducted for smooth glass beads are 20%,50% and 80% respectively, with corresponding unit weights are 14.1kN/m3 , 14.4kN/m3 and 14.7kN/m3 respectively and for etched glass beads the different unit weights at which tests were conducted are 14.65 KN/m3 ,14.93 KN/m3 and 15.2 KN/m3 with corresponding relative densities of 30.86%, 54.5% and 76.48% respectively. Most of the direct shear tests were conducted to shear strain in excess of 30%. The stress strain response was observed and recorded, and the shear strength and dilatancy parameters were obtained for each relative density and normal stresses. The normal stress was varied from 50 kPa to 400 kPa. The tests were conducted on smooth and etched glass beads; the etched surface of glass beads was obtained by keeping the glass beads in a bath of hydrochloric acid. Also in the present work a correlation between peak friction angle, dilatancy angle and critical state friction angle was obtained for glass beads and etched glass beads. The present data was also compared with those of established correlations by Bolton (1986) and Kumar et.al (2007).

Keywords: Strength, Dilatancy, Relative density, Peak friction angle, Critical state, Correlations, Glass beads

I. INTRODUCTION

An assembly of particles will form a granular material; its mechanical behavior depends on the size and shape of the particles, their arrangement, particle-to-particle friction, associated pore spaces, and the degree of saturation. When deformations take place in granular materials, the external forces may produce internal fabric changes, which may caused by rolling, particles sliding and interlocking, these changes will produce a different response of the material behavior.

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