Rate-dependent undrained shear behavior of saturated clay
- Northeastern Univ., Boston, MA (United States). Dept. of Civil Engineering
- Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Civil and Environmental Engineering
The paper describes results from 250 K{sub 0} consolidated-undrained triaxial compression tests on resedimented Boston blue clay using a computer-automated triaxial apparatus with lubricated end platens and a midheight pore-pressure measurement device. Specimens were consolidated to four over consolidation ratios (OCR = 1, 2, 4, or 8), and for each OCR, undrained shear was performed using four axial strain rates (0.05%, 0.5%, 5%, and 50%/h). The results show that the undrained strength (s{sub u}) rate sensitivity (percent increase in s{sub u} per log cycle strain rate) across the two fastest strain rates does not vary with OCR and equals about 9%. However, across the three slower rates, increases in OCR cause a consistent decrease in the rate sensitivity that reaches zero at OCR = 8. For high OCR clay, increases in s{sub u} (if they occur) are caused by lower shear-induced pore pressures since the effective stress envelope at the peak strength does not vary with strain rate. For low OCR clay, increases in s{sub u} are caused by both lower shear-induced pore pressures and increases in the mobilized friction angle. A simple technique is proposed for modeling the rate dependent stress-strain curves of over consolidated clay.
- OSTI ID:
- 207854
- Journal Information:
- Journal of Geotechnical Engineering, Vol. 122, Issue 2; Other Information: PBD: Feb 1996
- Country of Publication:
- United States
- Language:
- English
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