Dynamic response of machine foundation resting on sand-granulated tyre rubber mixtures

Building and Construction Engineering Department, University of Technology, Baghdad, Iraq

^* Corresponding author: ffhhhzmr@yahoo.com

Abstract

This paper examines the dynamic response of machine foundation resting on sand mixed with granular rubber of sizes (0.07-3) mm to improve the vibration attenuation and to reduce the settlement of the foundation. Granular rubber used is the product of hashing scrap tyres to small pieces in a tyre factory of Babylon in Iraq. Forty Model tests were carried out in a steel box of size (1200x1200x900) mm using a steel square footing of size (200x200x20) mm and a vertically acting rotating-mass type mechanical oscillator to apply a harmonic vertical mode of vibration. Karbala sand was used in this study with two relative densities (loose and medium) mixed with granular rubber ratios of (4%, 8% and 12%) of dry sand for different depths of mixing of (0.25 B, 0.5 B and 1B). The effect of relative density, frequency, depth of mixing and mixing ratio were studied. The results showed that the displacement amplitude and the settlement of machine foundation resting on dry sand granular rubber mixtures decreased with increasing mixing ratio and mixing depth. The optimum mixing ratio and mixing depth for loose state are (8% and 0.5B) at 69 Hz frequency while they are (12% and 1B) at 80 Hz frequency. For medium state they are (8% and 1B) for both frequencies. The settlement became constant after few seconds of vibration application when the foundation resting on sand mixed with optimum granular rubber content.