Rate-Dependent Undrained Shear Behavior of Saturated Clay
Publication: Journal of Geotechnical Engineering
Volume 122, Issue 2
Abstract
The paper describes results from 25 K o 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 overconsolidation 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 u ) rate sensitivity (percent increase in s 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 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 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 overconsolidated clay.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Alberro, J., and Santoyo, E.(1973). “Long term behavior of Mexico City clay.”Proc., 8th Int. Conf. on Soil Mech. and Found. Engrg., 1, 1–9.
2.
Berre, T., and Bjerrum, L.(1973). “Shear strength of normally consolidated clays.”Proc., 8th Int. Conf. on Soil Mech. and Found. Engrg., 1, 39–49.
3.
Bishop, A. W., Blight, G. E., and Donald, I. B. (1960). “Closure to `Factors controlling the strength of partly saturated cohesive soils.”' Res. Conf. on Shear Strength of Cohesive Soils, ASCE, New York, N.Y., 1027–1042.
4.
Bjerrum, L., Simons, N., and Toblaa, I.(1958). “The effect of time on the shear strength of a soft marine clay.”Proc., Conf. on Earth Pressure Problems, 1, 148–158.
5.
Casagrande, A., and Wilson, S. D.(1951). “Effect of rate of loading on the strength of clays and shales at constant water content.”Géotechnique, London, U.K., 2(3), 251–263.
6.
Germaine, J. T., and Ladd, C. C. (1988). “Triaxial testing of saturated cohesive soils.”Advanced Triaxial Testing of Soil and Rock, ASTM Spec. Tech. Publ. No. 977, ASTM, Philadelphia, Pa., 421–459.
7.
Graham, J., Crooks, J. H. A., and Bell, A. L.(1983). “Time effects on the stress-strain behavior of natural soft clays.”Géotechnique, London, U.K., 33(3), 327–340.
8.
Hight, D. W. (1983). “Laboratory investigations of sea bed clays,” PhD thesis, Imperial College, London, U.K.
9.
Ladd, C. C., and Foott, R.(1974). “New design procedure for stability of soft clays.”J. Geotech. Engrg. Div., ASCE, 100(7), 763–786.
10.
Ladd, C. C., Foott, R., Ishihara, K., Schlosser, F., and Poulos, H. G. (1977). “Stress-deformation and strength characteristics.”Proc., 9th Int. Conf. on Soil Mech. and Found. Engrg., Tokyo, 421–494.
11.
Ladd, C. C., Williams, C. E., Connell, D. H., and Edgers, L. (1972). “Engineering properties of soft foundation clays at two south Louisiana levee sites.”Res. Rep. No. R72-26, Massachusetts Inst. of Technol., Cambridge, Mass.
12.
Lefebvre, G., and LeBoeuf, D.(1987). “Rate effects and cyclic loading of sensitive clays.”J. Geotech. Engrg., ASCE, 113(5), 476–489.
13.
Poulos, S. J. (1964). “Report on control of leakage in the triaxial test.”Res. Rep. for U.S. Army Corps of Engrs. Wtrwys. Experiment Stn., Harvard Univ., Cambridge, Mass.
14.
Richardson, A. M. (1963). “The relationship of the effective stress-strain behavior of a saturated clay to the rate of strain,” ScD thesis, Massachusetts Inst. of Technol., Cambridge, Mass.
15.
Richardson, A. M., and Whitman, R. V.(1963). “Effect of strain-rate upon undrained shear resistance of a saturated remoulded fat clay.”Géotechnique, London, U.K., 13(4), 310–324.
16.
Rowe, P. W., and Barden, L.(1964). “Importance of free ends in triaxial testing.”J. Soil Mech. and Found. Div., ASCE, 90(1), 1–27.
17.
Schmidt, B.(1966). “Discussion of `Earth pressure at rest related to stress history,' by E. W. Brooker and H. O. Ireland,”Can. Geotech. J., 3(4), 239–242.
18.
Sheahan, T. C. (1991). “An experimental study of the time-dependent undrained shear behavior of resedimented clay using automated stress path triaxial equipment,” ScD thesis, Massachusetts Inst. of Technol., Cambridge, Mass.
19.
Sheahan, T. C.(1995). “Interpretation of undrained creep tests in terms of effective stresses.”Can. Geotech. J., 32, 373–379.
20.
Sheahan, T. C., and Germaine, J. T.(1992). “Computer automation of conventional triaxial equipment.”Geotech. Testing J., 15(4), 311–322.
21.
Sheahan, T. C., Germaine, J. T., and DeGroot, D. J. (1993). “Laboratory data acquisition: a practical guide to system selection and implementation.”Geotech. Spec. Publ. No. 37, ASCE, New York, N.Y., 42–56.
22.
Taylor, D. W. (1943). “Cylindrical compression research program on stress-deformation and strength characteristics of soils.”9th Progress Rep. to U.S. Army Corps of Engrs. Waterways Experiment Station, Massachusetts Inst. of Technol., Cambridge, Mass.
23.
Vaid, Y. P., and Campanella, R. G.(1977). “Time-dependent behavior of undisturbed clay.”J. Geotech. Engrg. Div., ASCE, 103(7), 693–709.
Information & Authors
Information
Published In
Copyright
Copyright © 1996 American Society of Civil Engineers.
History
Published online: Feb 1, 1996
Published in print: Feb 1996
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.