Sensitive clays in Canada have been found to be prone to cyclic softening (Lefebvre et al. 1989 and Hanna and Javed 2014) which is characterized as a loss of stiffness under cyclic loading (Vaid and Zergoun 1994, Boulanger and Idriss 2007). Constitutive modeling of sensitive clays has focused on static loading (e.g. Grimstad et al. 2012). Recently, Taiebat et al. (2010a) used the SANICLAY constitutive model (Taiebat et al. 2010b) for a seismic slope stability problem. Seidalinov and Taiebat (2014) then modified the constitutive model by incorporating a bounding surface algorithm to better model the dynamic behavior of clays. Although viscous effects are not integrated in the current formulation, this constitutive model is currently the best suited for problems involving cyclic softening. However, a constitutive model derived specifically for cyclic softening would be beneficial.

The 3D constitutive model previous derived (see here) will be combined with the concept of damage mechanics in order to create a constitutive model for sensitive clays. This model will be used for problems involving cyclic softening and will be derived based on published literature and lab tests.

References:

Grimstad, G., Andresen, L., & Jostad, H. P. (2012). “NGI‐ADP: Anisotropic shear strength model for clay”. International Journal for Numerical and Analytical Methods in Geomechanics, 36(4), 483-497.

Hanna, A. M., & Javed, K. (2014). “Experimental Investigation of Foundations on Sensitive Clay Subjected to Cyclic Loading.” J Geotech Geoenviron Eng, 140(11), 04014065.

Lefebvre, G., LeBoeuf, D., & Demers, B. (1989). “Stability threshold for cyclic loading of saturated clay.” Canadian Geotechnical Journal, 26(1), 122-131.

Seidalinov, G., & Taiebat, M. (2014). “Bounding surface SANICLAY plasticity model for cyclic clay behavior.” Int. Journal for Numerical and Analytical Methods in Geomechanics, 38(7), 702-724.

Taiebat, M., Kaynia, A. M., & Dafalias, Y. F. (2010a). “Application of an anisotropic constitutive model for structured clay to seismic slope stability.” J Geotech Geoenviron Eng, 137(5), 492-504.

Taiebat, M., Dafalias, Y. F., & Peek, R. (2010b). “A destructuration theory and its application to SANICLAY model.” Int. J. for Numerical and Analytical Methods in Geomechanics, 34(10), 1009-1040.

Zergoun, M. and Vaid, Y.P., (1994). “Effective stress response of clay to undrained cyclic loading.” Canadian Geotechnical Journal, 31(5), pp.714-727.