Volume 15, Issue 1 (March 1992)
Total Stress Probe Determination of Clay Slurry Density
The progress of sedimentation, self-weight consolidation, and gain in surface strength of a hydraulic clay fill were observed by monitoring the density improvement of the clay slurry with time. A practical method of measuring the in situ slurry density profile with depth is to employ a submersible gamma-source, backscattertype nuclear density gauge. A slurry consolidation test in the laboratory has demonstrated that above 1.5 times the liquid limit, the horizontal and vertical total stresses are equal. Hence, from the horizontal total stress measurements with a vertical probe, the in situ vertical total stress profile of the slurry can be obtained. In principle, the integration of the density profile with depth gives the vertical total stress profile. Therefore, an estimate of the density can be made from the gradient of the vertical total stress with depth. Comparisons of field measurements of the total stress profile of a clay slurry in a reclamation project using the total stress probe and the density profile by the nuclear density gauge demonstrates this principle, thus confirming that the total stress probe with appropriate data interpretation can be used to measure the density of an in situ clay slurry around its surface.