Effect of Embedment Depth for Circular Footing on the Amplitude of Displacement under Dynamic Load

Abstract

The effect of the embedment depth of a circular footing resting on dry sand and subjected to dynamic load on the amplitude of soil displacement (Az) was investigated the present study. In order to simulate the conditions occurring in the field, a special testing apparatus with accessories was designed and manufactured to study the effect of dynamic load on soil. A total of 18 cases were examined to take into account the effects of different parameters, including different frequencies (0.5, 1, and 2 Hz); relative densities (medium sand, R.D=50% and dense sand, R.D=80%); and corresponding unit weights (17.52 kN and 18.33 kN). All tests were carried out under load amplitude of 0.5 tons. The behaviour of the soil underneath the footing was examined by measuring the amplitude of displacement AZ using a vibration meter placed at a set depth (B) under the footing. It was found that when the embedment depth is changed from zero (at surface) to 0.5 B and then to B the value of amplitude of the displacement Az is reduced. The percentage of reduction in Az was about 4 to 39 % at depth 0.5 B, and about 37-77 % at depth B.