Seepage-Induced Acoustic Emission in Granular Soils

This technical paper presents the results of a study on detecting excessive seepage in granular soils by monitoring the seepage-induced acoustic emission (AE). The laboratory experiments and data analyses were performed using specially designed data acquisition instruments and computer-based data analysis devices. The monitored data were analyzed using three methods, namely, amplitude, time, and frequency domain analyses. The analysis results showed that the seepage-induced AE in the test soils were broadband Gaussian signals which were zero mean, normally distributed, and leptokurtic. All of the measured autospectral density functions showed that the most prominent AE activities occurred within a frequency range of about $0.8–10\mathrm{kHz}$ . Based on acoustic similarity laws and a graphical fitting method, the test results were subjected to dimensional analysis. The results of this analysis provided a relationship between a nondimensional sound pressure level and a nondimensional frequency, in which AE intensity, seepage velocity, soil, and permeant properties were interrelated. This relationship provided a fundamental basis for detecting excessive seepage using the monitored seepage-induced AE intensity.