Past Consolidation Stress Estimates in Cretaceous Clay

Abstract

It is shown in this paper that in a highly overconsolidated undis turbed clay, due to natural unloading, most of the strain was recovered in the vertical direction, but not in the horizontal direction. Consolidation tests were performed on both undisturbed and remolded specimens, with the specimens oriented as in conventional tests (V‐test) and at right angle (H‐test). Estimated precompression stress for V‐tests was considered inadequate to define the max imum past consolidation stress. Estimated precompression stress from H‐tests was comparatively higher, and gave a more realistic estimate for maximum past consolidation stress. However, when the soil was allowed to swell at a low stress, the H‐tests also behaved similar to the V‐tests. It is postulated, that, the lesser the degree of strain recovery since the unloading of the soil, the better is the estimate for precompression stress. Electron micrographs showed no pre ferred particle orientation for undisturbed specimens in the natural state and after loading to 26 tsf (2.6 MPa). For remolded samples, conventional tests yielded accurate values of maximum precompression stress.