THE REACTION OF CLAYS TO SAMPLING STRESS RELIEF
The paper describes investigations into the influence of stress relief caused by sampling on the undrained stress-strain behaviour of normally consolidated clays. The study was conducted on two clays, kaolin and illite, manufactured in the laboratory from consolidated slurries. In situ behaviour was measured from clay specimens consolidated to in situ stresses in the triaxial cell and then tested undrained from these in situ stresses without unloading. Samples were prepared from consolidated blocks of material which were unloaded and stored for various times before being tested in undrained compression. Unloadings equivalent to appreciable sampling depths were simulated. The tests on both clays showed that, compared with the in situ soil, samples suffered considerable loss in strength, increase in failure strain and produced appreciably different effective stress paths to failure. This behaviour became more pronounced with increasing sample age and was accompanied by dissipation of residual negative pore pressure in the samples. The strength losses were more acute in the kaolin compared with the less permeable illite. The results indicate that the unconsolidated undrained test is misleading for predicting in situ undrained behaviour where stress relief is appreciable. It was found that in situ behaviour of these young and relatively insensitive clays could be reproduced with reasonable accuracy from samples in the consolidated undrained test provided that the samples are reconsolidated to the in situ stresses. These conclusions apply to relatively deep samples of young, intact clays of relatively low sensitivity. (Author/TRRL)
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Availability:
- Find a library where document is available. Order URL: http://worldcat.org/issn/00168505
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Corporate Authors:
Institution of Civil Engineers
One Great George Street, Westminster
London, United Kingdom SW1P 3AA -
Authors:
- Kirkpatrick, W M
- Khan, A J
- Publication Date: 1984-3
Media Info
- Features: Figures; References; Tables;
- Pagination: p. 29-42
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Serial:
- GEOTECHNIQUE
- Volume: 34
- Issue Number: 1
- Publisher: Thomas Telford Limited
- ISSN: 0016-8505
Subject/Index Terms
- TRT Terms: Age; Clay; Consolidation; Deformation curve; Effective stress; Evaluation and assessment; Failure; Field tests; Forecasting; Illites; Kaolin; Pore pressure; Samples; Sampling; Saturated soils; Soil stabilization; Strength of materials; Stress relieving; Stresses; Tests; Triaxial shear tests; Undrained strength
- Uncontrolled Terms: Undrained conditions; Undrained soils
- Old TRIS Terms: Insitu methods; Negative pore pressures
- ITRD Terms: 1757: Age; 4177: Clay; 5791: Consolidation (soil); 9020: Evaluation (assessment); 5520: Failure; 132: Forecast; 6226: In situ; 6251: Sample (mater); 6253: Sampling; 5544: Strength (mater); 5575: Stress (in material); 6255: Test; 5782: Undrained soil
- Subject Areas: Geotechnology; Highways;
Filing Info
- Accession Number: 00390493
- Record Type: Publication
- Source Agency: Transport Research Laboratory
- Files: ITRD, TRIS
- Created Date: Mar 29 1985 12:00AM