Several tests (both laboratory and full-scale) were conducted to assess the potential of AGWA-II thermal conductivity sensors to measure soil suction in geotechnical engineering applications. The tests conducted in the laboratory included examining the response of the sensors submerged in water, calibrating the sensors in a pressure plate, and measuring soil suction in undisturbed soil specimens. Initial tests conducted on the sensors indicated some inaccuracies associated with the linear calibration curves suggested by the manufacturer. The calibration results showed that the calibration curves for the sensors were bilinear with a breaking point at about 175 kPa. Reasonable agreement was found between the calibration curves obtained in this study and those provided by the manufacturer for matric suction ranging from 0 to 175 kPa. However, large deviations in the calibration curves were observed at suction above 175 kPa. With the calibrated sensors, a testing program was carried out by measuring soil suction in undisturbed soil specimens. Upon the completion of the laboratory tests, the sensors were installed in the subgrade soils of an indoor test track for long-term monitoring. The sensor outputs were found to be relatively consistent and stable with time.
Samenvatting