Mohammed Y. Fattah, Nahla M. Salim, Rusul J. Haleel
Abstract: Liquefaction is a phenomenon that occurs during earthquakes, and leads to ground failure. Water-saturated, well sorted, fine grain sands and silts behave as viscous fluid as a result of liquefaction. This behavior of fluids is very different than solids behavior. This paper presents and discusses the results of 54 experimental model tests, all of them were performed on saturated sand under vertical dynamic traffic load using different relative densities (medium and dense), different shapes of footing (square and circular), and different embedment depths (at surface and at depth B) where B is the width of footing. It was concluded that by increasing the relative density of sand, the surface settlement decreases, when sands relative density increases from 60 % to 80 %, the reduction of the surface settlement for surface footing condition was about 26 to 72 % at (0.5 ton, 0.5 Hz 2 ton, 1 Hz), and 27 74 % at (0.5 ton, 0.5 Hz 2 ton, 1 Hz) reduction for embedded footing condition models. Also the embedment of footing in dense sand reduces the settlement more than medium sand, because the dense soil is the stiffest. The amplitude of displacement (Az) decreased at both depths B and 2B, when soil relative density increased, the percentage of reduction in (Az) was about (4-93) % at depth B, and about (37-77) % at depths 2B, when soil relative density increased from (60 %) to (80 %). Also the displacement amplitude (Az) of the surface square footing is less than that of circular footing at both depths B and 2B.
Keywords: Liquefaction, machine foundation, sand, relative density, frequency