Determination of Soil Characteristic Frequency Using Acoustic Techniques

Based on the Biot's frequency dependent elastic wave propagation theory. The characteristic frequency of sandy soils is measured. In order to determine the characteristic frequency an inverse quality factor (1/Q) versus frequency sweep curve is used. In this paper, to compute the inverse quality factor two different techniques are adopted. The first technique utilizes the continuously supplied sinusoidal wave with different frequencies and measurements were made at two receivers which have different distances from the source. From the difference of amplitudes of two receivers the attenuation was computed. The second technique utilizes the free vibration decay curve to compute the attenuation. The characteristic frequency is clearly observed in this study from the 500 Hz to 4000 Hz frequency ranges. Furthermore, the response of two different techniques shows approximately the same results.