Repair, Evaluation, Maintenance, and Rehabilitation Research Program. Geotechnical Applications of the Self Potential (SP) Method. Report 1. The Use of Self Potential in the Detection of Subsurface Flow Patterns in and Around Sink

摘要

Self potential (SP) measurements were effectively used in the detection of surface and subsurface drainage around a sinkhole. The same SP technique was also able to track an apparent subsurface flow path for over 600 ft from one sinkhole into another sinkhole. Confirmation of the SP data was obtained by visual observation, electrical resistivity measurements and geological studies. The use of this geophysical technique was evaluated in and around sinkholes in a karst area of west central Virginia. The SP electrode configuration consisted of a double ring of electrodes circumferentially located around each sinkhole. Two reference electrodes were used in taking SP measurements. One reference electrode was located outside the rings of electrodes, and the other was located in the center of one of the sinkholes. Once a major drainage path around the sinkhole was detected, an array of electrodes was used to track the flow path. Although SP data varied significantly for individual electrodes during the 6-month testing period, the relative values between electrodes were consistent. This finding was also true if the position of the reference electrode was changed. It appeared that changes in precipitation and temperature had a great effect on the variation of SP data over the testing period. Keywords: Subsurface drainage; Surface drainage.