RESPONSE OF CIRCULAR MACHINE FOUNDATION RESTING ON SANDY SOIL TO HARMONIC EXCITATION

This paper focuses on the effect of the machine's circular foundation on the variation of surface settlement, vertical displacement and stress with a number of cycles. A special setup was designed and manufactured to simulate the vertical vibration of a machine foundation. Six laboratory model footings were prepared on medium and dense dry sand separately. A circular steel model of (150 mm) diameter was used to represent the footing. The models were tested under dynamic load amplitude of 0.25 ton and different frequencies of 0.5, 1, and 2 Hz. It was found that the rate of increase in settlement decreased remarkably when increasing the frequency for both types of sand. While increasing the soil relative density under the same load and frequency resulted in a decrease of the settlement. Moreover, the amplitude displacement decreased when increasing frequency and relative density. The resulting stress due to the dynamic load below the foundation decreased with depth. Besides, there is a little difference in the induced dynamic stress between the depths B and 2B. The stress had increased when the frequency and sand relative density were decreased under the same load amplitude.