EVALUATION OF DYNAMIC PROPERTIES OF SANDS USING RESONANT COLUMN APPARATUS

Abstract

Evaluation of dynamic behaviour of sand has been of prime importance for many engineering problems such as those caused by earthquake, wind loading etc. Dynamic loads for short duration on soil cause small strain levels. Resonant column device has been used to measure the small strain stiffness and damping characteristics of sands extensively in last few decades. This study focuses the measurement of dynamic properties of sand and the procedure for laboratory testing is also described. The apparatus is in fixed free condition and driven system allows specimen to be subjected to fundamental modes of vibration in torsion and flexure. It is well known that the behaviour of sands depends upon relative density and confining pressure. The objective of this dissertation is to evaluate the variation of shear modulus, damping ratio, modulus of elasticity and Poisson’s ratio with the shear strain ranging from 0.0001% to 0.1%. In the present study, torsional tests and flexural tests are performed on Solani sand in order to get required dynamic properties of Solani sand. The sand is collected from the bed of Solani River adjacent to Roorkee, India. The effects of confining pressure (50kPa, 100kPa & 150kPa) and relative density (35%, 55% & 70%) are discussed. It is observed that increase in confining pressure increases shear modulus of sands and reduces damping ratio. Also, the increase in relative density of sand increases shear modulus and decreases damping ratio of sands. Also, Poisson’s ratio of Solani sand is determined which increases with the increase in shear strain. The problems faced in testing are also discussed.