In Situ Evaluation of Radioisotope Cone Penetrometers in Clays

A comprehensive site investigation was performed at a 12-year-old man-made island in Singapore, which was reclaimed using dredged clay lumps. The objective of the site investigation was to evalute the performance of the radioisotope (RI) cone penetrometers to measure in situ wet density and water content, which are the two important parameters in the characterization of soils formed from clay lumps. The site investigation program included RI cone penetration tests, high quality soil sampling, and laboratory testing. The in situ water content and wet density profiles measured with RI cone penetrometers were compared with data obtained independently from the laboratory tests on undisturbed samples. The comparison shows very good agreement, and 92% of the RI cone measurements were found to be within ±5% of the laboratory measurements.