Optimum jute geotextile spacing in reinforced sand: shear modulus and damping variation

This study examines the inclusions of jute geotextile (JG) sheets on shear modulus (G) and damping ratio (D) of dry sand. Resonant column (RC) and bender element (BE) tests were conducted on sand specimens reinforced with varying numbers of JG sheets under different confining pressures and for a wide range of input voltages. The inclusion of JG sheets in sand enhances significantly not only its shear modulus but also the damping ratio. The increase in the value of G with a decrease in the spacing between the sheets was, however, noted to occur only up to a certain optimum spacing of JG sheets. The small-strain shear modulus (G0) obtained from BE tests further confirmed that the reinforcement-induced improvement in G0 becomes maximum corresponding to the optimum spacing of sheets. This optimum centre to centre spacing (s) of JG sheets was noted to be 13.9t, where t is the thickness of the geotextile sheet. The damping ratio, on the other hand, increases continuously with a decrease in the spacing between the sheets. For the chosen JG reinforced sand, non-linear power law empirical expressions were introduced for predicting G0 and Dmin for a given value of σ3 in terms of s/t ratio.