Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4743193 | Engineering Geology | 2016 | 9 Pages |
•K0 was measured on a highly plastic fissure tertiary clay.•σ'pc was remembered but “short-term” memory was lost.•Jaky (1944) was found to be of little use on the clay.•Friction angle was of no use to estimate K0(nc).
The present study evaluated the earth pressure at rest, K0, of Søvind Marl, a highly overconsolidated Eocene clay. This clay exhibits extremely high plasticity indices of up to 300%, a highly fissured structure, and preconsolidation stresses up to 6800 kPa. Continuous Loading Oedometer (CLO) tests at a constant rate of strain were performed in the Danish CLO apparatus. This apparatus applies test water at 200 kPa and measures total horizontal stresses via pressure gauges placed in a stiff oedometer ring. Horizontal and vertical stresses were measured from in situ stresses to various stress levels to estimate continuous K0 development in the clay. Normally consolidated earth pressures at rest were 0.42 and 0.68 for Søvind Marl at two different ages. Overconsolidated K0, K0(oc), reached values as high as 6 to 8 in the in situ stress range. The correlation between K0(oc) and the overconsolidation ratio, OCR, reported by Meyerhof in 1976 was inconsistent with the K0(oc) development of Søvind Marl. However, the development of OCR in the laboratory under the previously applied test stresses, OCRlab, as an alternative to preconsolidation stresses, showed congruent results regardless of sample age when an α-value of 1.05 was used.