Karst cavities beneath bored cast in situ piles are hazardous to the stability of infrastructure projects. Therefore, it is important to detect these karst cavities during the construction of piles. An improved sonar method for the detection of karst cavities beneath piles based on signal instantaneous phase analysis is presented here. Instantaneous phase difference intensity (IPDI) is defined as an index that assesses the similarity of signal instantaneous phase between two receivers. IPDI peak is an effective index for the arrival of reflection from a cavity even when there is strong contamination from multiple reflected waves and noise. A prototype using the IPDI based method was developed and tested at a field site. Azimuthal detection is achieved by rotating the downhole probe and controlling its azimuth with a 3D electric compass in the downhole tool. Results demonstrate that the IPDI-based method and prototype instrumentation are effective for detecting cavities beneath pile.
Presentation Date: Tuesday, September 17, 2019
Session Start Time: 8:30 AM
Presentation Time: 11:25 AM
Presentation Type: Oral