INTERNAL EROSION DETECTION-ASSESSMENT AND EXPERIENCES FROM A BLIND TEST USING TEMPERATURE, RESISTIVITY, SELF POTENTIAL, AND VISUAL INSPECTION
Resistivity, Self Potential, and Temperature are three indirect methods for leakage monitoring in embankment dams. BC Hydro (Canada), Elforsk AB (Sweden) and EBL represented by Statkraft Gr(o)er (Norway) jointly conducted a research project in order to test the performance of those methods at the unique test site at R(o)vatn in Norway. The project team was separated into a design group? and a monitoring group?in order to make a blind test. A pre-study was carried out by the monitoring group?in order to estimate the detection level of the electrical methods, and suggest appropriate defect design. Three defects were constructed carefully, but an undesired leakage area occurred, giving totally four defects. All defects were small, and none should have been detected according to the predictions. However, the pre-study assumed an investigation approach where anomalies due to material differences should be able to detect. Due to the different water levels in the reservoir a monitoring approach could be adopted that increased the detection level of the methods. All four defects were detected by temperature measurements and by visual inspections. Three defects were detected by resistivity measurements using the monitoring approach. The conditions for the SPmeasurements were severe, but one defect was indicated as a weak anomaly. No final conclusion about the general application of resistivity and SP can be made until the electrical properties of the soil material have been determined. The experience indicates that resistivity and SP seems less sensitive than temperature and visual inspections, but the conditions at the test were in some aspects favorable to the latter methods. The test shows that temperature, resistivity, and SP may be used at investigations but the best result will be achieved at monitoring. This agrees well with the experience gained from the ongoing long term monitoring research in Sweden.
Internal erosion Temperature Resistivity Self potential Seepage detection
Sam Johansson (A)ke Nilsson Torleif Dahlin Johan Friborg Steve Garner Pontus Sj(o)dahl
HydroResearch Sam Johansson ABSE-183 65 T(A)BY, Sweden SwedPower ABSE-162 16 V(a)lingby, Sweden Lund University Sweden Hydro Research ABSweden BC Hydro Canada
国际会议
西安
英文
1-11
2005-11-01（万方平台首次上网日期，不代表论文的发表时间）