Measuring radial total stresses on model suction caissons in clay

Miniature total pressure transducers (TPTs) were incorporated on model suction caissons in order to measure changes in radial stress during installation and loading of the caissons. The accuracy of TPTs in clay was first assessed by calibration tests at both 1g and in a geotechnical centrifuge at up to 120g. Calibration tests in a modified triaxial apparatus showed that the accuracy of the TPTs under loading, unloading, cyclic loading, and sustained loading was better than 92.5%. The initial readings of the TPTs were also found to change only slightly on transfer among air, water, and soil, in spite of differences in the heat exchange environment. The cross-sensitivity of TPTs to an axial load of 300 N on the caisson was insignificant. The accuracy of TPTs in water in the centrifuge was better than 96 %. The TPTs also gave reasonable measurements of radial stresses generated on the outer wall of suction caissons during penetration in clay at 1208, as assessed by comparison with stress changes predicted using the strain path method.