American Society of Civil Engineers

Application of an Anisotropic Constitutive Model for Structured Clay to Seismic Slope Stability

by Mahdi Taiebat, (corresponding author), M.ASCE, (Assistant Professor, Dept. of Civil Engineering, Univ. of British Columbia, Vancouver, BC, Canada V6T 1Z4 E-mail:, Amir M. Kaynia, M.ASCE, (Discipline Leader, Earthquake Engineering, Norwegian Geotechnical Institute, P.O. Box 3930 Ullevaal Stadion, N-0806 Oslo, Norway. E-mail:, and Yannis F. Dafalias, M.ASCE, (Professor, Dept. of Civil and Environmental Engineering, Univ. of California at Davis, Davis, CA 95616; and Dept. of Mechanics, Faculty of Applied Mathematical and Physical Sciences, National Technical Univ. of Athens, Zographou 15780, Greece. E-mail:

Journal of Geotechnical and Geoenvironmental Engineering, Vol. 137, No. 5, May 2011, pp. 492-504, (doi:

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Document type: Journal Paper
Abstract: The anisotropic nature of response and degradation of shear strength from the undisturbed condition to the remolded state are two fundamental and challenging aspects of response in some clay deposits. This paper presents a comprehensive, yet flexible and practical, version of the SANICLAY model and its application to a seismic slope-stability problem. The model is based on the well-known isotropic modified Cam-Clay model with two additional mechanisms to account for anisotropy and destructuration. The model has been efficiently implemented in a three-dimensional (3D) continuum, coupled, dynamic, finite-difference program. The program has been used to analyze the seismic response of clay slopes to gain better insight into the role of the previously mentioned parameters in real applications. Different aspects of the model, including anisotropy and destructuration, and their effects on the earthquake-induced strains and deformations in the slope have then been explored and presented. By providing a link between the model parameters and the soil’s undrained shear strength, which is a well-known engineering parameter, a benchmark comparison has been made between the results of the present advanced model and those of an engineering approach. To this end, a modified Newmark sliding-block analysis has been used, in which the yield acceleration is gradually reduced as block sliding progresses during the earthquake. It is observed that although the two analyses display the same trends, the modified Newmark sliding-block method provides conservative results compared with those obtained from the developed simulation model.

ASCE Subject Headings:
Constitutive models
Numerical models
Seismic effects
Slope stability

Author Keywords:
Constitutive model
Structured clay
Numerical modeling
Seismic slope stability