Evaluation of Yielding in Unsaturated Clays Using an Automated Triaxial Apparatus with Controlled Suction

  • James Blatz
  • David Anderson
  • Jim Graham
  • Greg Siemens
Conference paper
Part of the Springer Proceedings in Physics book series (SPPHY, volume 93)


Research in the field of unsaturated soil mechanics for high plastic clays is very active. One area of considerable current interest is development of general constitutive models for unsaturated clay based sealing materials in a frame work that can be implemented in numerical modeling tools (Alonso et al. 1990, Delage and Graham 1995, Toll 1990). In particular, more quantitative information is required to define the features of yielding, failure and strain hardening for predictive modeling applications. Soil suction must be controlled and independently measured in laboratory tests. This will allow examination of behaviour along any stress path that can be expected to occur in engineering applications which will provide the necessary material information to calibrate and validate proposed constitutive frameworks.

This paper presents details of laboratory tests in a custom triaxial system with stress path automation and independently controlled and measured suction (Blatz and Graham 2000, 2003). Details describing the equipment will be given along with selected results for the yield, strength, and strain hardening behavior of a high-plastic sand-clay material at suctions from 5 MPa to 160 MPa and isotropic pressures from 1 MPa to 6 MPa. The results demonstrate the importance of independent measurement and control of suction along well controlled loading paths for interpreting the behaviour of unsaturated high plastic clays.


Triaxial Test Unsaturated Soil Stress Path Volumetric Shrinkage Soil Suction 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Alonso, E.E., Gens, A., and Josa, A. 1990. A constitutive model for partially saturated soils. geotechnique, 40: 405–430.Google Scholar
  2. Blatz, J.A., and Graham, J. 2003. Elastic plastic modeling of unsaturated high plastic clay using results from a new triaxial test with controlled suction. Géotechnique Special Symposium in Print on Unsaturated Soils, 53(1): 113–122.Google Scholar
  3. Blatz, J.A., and Graham, J. 2000. A method for controlled suctions in triaxial testing. Géotechnique, 50(4): 465–470.Google Scholar
  4. Blatz, J.A., Tang, G.X., Graham, J., and Wan, A. 1999. Psychrometer techniques for measuring suction in the triaxial test. Proc. of 52nd Canadian Geotechnical Conference, Regina, Vol. 1, pp. 617–622.Google Scholar
  5. Cui, Y.J. and Delage, P. 1996. Yielding and plastic behaviour of an unsaturated compacted silt. Geotechnique, 46(2): 291–312.Google Scholar
  6. Cunningham, M.R., Ridley, A.M., Dineen, K., and Burland, J.B. 2003. The mechanical behaviour of a reconstituted unsaturated silty clay. Géotechnique Special Symposium in Print on Unsaturated Soils, 53(2): 183–194.Google Scholar
  7. Delage, P. and Graham, J. 1995. Understanding the behavior of unsaturated soils requires reliable conceptual model. State of the Art Report, Proceedings, 1st Int. Conf. on Unsaturated Soils, Paris, France, 1995, 1223–1256.Google Scholar
  8. Escario, V. and Sàez, J. (1986). The shear strength of partly saturated soils. Géotechnique 36, No. 3, 453–456.Google Scholar
  9. Fredlund, D.G. and Rahardjo, H. 1993. Soil Mechanics for Unsaturated Soil. A Wiley-Interscience Publication. John Wiley & Sons, Inc., New York, NY.Google Scholar
  10. Graham, J., Chandler, N.A., Dixon, D.A., Roach, P.J., To., T., Wan, A.W.L. 1997. The buffer container experiment: results, synthesis, issues. AECL Whiteshell laboratories, Pinawa, Manitoba. AECL-11746.Google Scholar
  11. Ridley A.M. and Burland, JB. 1993. A new instrument for the measurement of soil moisture suction. Geotechnique 43(2): 321–324.Google Scholar
  12. Tang, G.X., Graham, J., Blatz J.A., Gray, M. and Rajapakse, R.K.N.D. 2002. Suctions, stresses and strengths in unsaturated sand-bentonite. Journal of Engineering Geology, 64(2): 147–156.Google Scholar
  13. Toll, D.G. 1990. A framework for unsaturated soils behavior (discussion). Geotechnique, 41(1): 159–161.Google Scholar
  14. Wheeler S.J., Sharma, R.S., and Buisson, M.S.R. 2003. Coupling of hydraulic hysteresis and stress — strain behaviour in unsaturated soils. Géotechnique Special Symposium in Print on Unsaturated Soils, 53(1): 41–54.Google Scholar
  15. Wheeler, S.J. and Sivakumar, V. 1995. An elasto-plastic critical state framework for unsaturated soil. Geotechnique, 45(1): 35–53.Google Scholar
  16. Wiebe, B.J. 1996. The effect of confining pressure, temperature, and suction on the strength and stiffness of unsaturated buffer. M.Sc. Thesis, Department of Civil and Geological Engineering, University of Manitoba, (Winnipeg, Manitoba).Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2005

Authors and Affiliations

  • James Blatz
    • 1
  • David Anderson
    • 1
  • Jim Graham
    • 1
  • Greg Siemens
    • 1
  1. 1.Department of Civil EngineeringUniversity of Manitoba WinnipegManitobaCANADA

Personalised recommendations