f A STUDY OF SOIL-PIPE FLOW AND INTERNAL EROSION BY ACOUSTIC TECHNIQUES

Internal erosion of soil pipes can lead to embankment failures, landslides, and gully erosion. This talk presents a lab study using both active and passive acoustic techniques to monitor and assess a soil pipe flow and internal erosion event. In active test, the phase slope method was employed to measure the P-wave velocity of soils under noisy and ever-changing conditions. The study showed that the variation of the P-wave velocity reflected the ongoing internal erosion processes such as the onset of soil pipe flow, the buildup of hydraulic pressure, the evolution of saturation, the variation of hydraulic pressure due to the change in flow rate, as well as aftermath events such as drainage, and relaxation. These observations can be analyzed and understood by using the concept of the effective stress and its relationship with the P-wave velocity.