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Numerical and Experimental Study of Accelerating the Swell Test from Clay-Based Materials by the Application of External Electrical Field

Deriszadeh, Mohammad 1; Wong, Ron C. K. 1
1 Civil Engineering, University of Calgary, Calgary, AB, Canada.

Conventional swell test on clays is known as a slow test in engineering literature and it can take months or years. In this study, the application of external electrical potential gradient through saturated clay samples subjected to fresh water has been investigated numerically and experimentally. Indeed, the electrical field provides a dominant source for ionic flows through the macro pores of the sample and therefore accelerates the process of ion extraction from it. A comprehensive mathematical framework has been developed for the proposed experiment. The mathematical framework is presented by coupling the multi-component mass (i.e., water and ionic species) transport through the pores of the sample in micro and macro scales. In the developed model a specific load transfer mechanism has been proposed through the sample to balance the stresses and pressures in micro and macro scales. Flows at both scales can influence this mechanism. The principle of electro-neutrality and probable electro-chemical reactions are considered in the model. The mathematical framework has been solved numerically using finite difference method. Numerical results are presented along with the detailed discussion on the mathematical framework. The results of numerical and experimental studies on clay shale and artificial bentonite cores saturated with sodium chloride solution have confirmed the positive effect of the application of electrical potential gradient in accelerating the swell test.


AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009