Swelling in shale is a coupled mechanical-hydraulic-chemical process. Special laboratory swell tests were conducted to examine the effects of different environmental loads on the total swell strain. A physical model for stress and strain partitioning has been proposed to explain the swelling interaction in micro-structural level. In addition, a framework based on the mass balance equations of fluid and solute has been developed to quantify the time-dependent coupled swelling process.
RÉSUMÉR: Le gonflement des shistes argileux est un phenomène qui fait intervenir un couplage des processus mecaniques, hydrauliques et chimiques. Des essais speciaux en laboratoire ont ete effectues pour etudier l'effet des charges reliee à des problèmes environmentaux sur la deformation totale de gonflement. On propose un modele physique pour la decomposition contraintes-deformations en vue de decrire les interactions de gonflement au niveau microstructure. Une formulation, basee sur l'ecriture de la conservation de la masse pour le fluide et le solute, à ete developee pour decrire l'evolution du gonflement en tant qu'un phenomène couple.
Schwellen in Ton ist ein gekoppelter mechanisch-hydraulisch-chemischer Prozess. Spezielle Schwellversuche wurden im Labor durchgefuehrt, urn den Einfluss verschiedener Umweltbelastungen auf den Gesamtwert der Schwelldehnung zu bestimmen. Es wurden ein physikalisches Modell zur Bestimmung der Spannungen und zur Unterteilung der Dehnungen entwickelt, um das Zusammenwirken von Schwellungen im Bereich der Mikrostruktur zu erklaren. Zudem wurde ein System entwickelt, das auf der Gleichung des Gleichgewichts der Massen von Fluessigkeit und aufgelsten Bestandteilen beruht, urn den zeitabhangigen, gekoppelten Schwellprozess zu quantifizieren.
Advances in testing of shale remain relatively stagnant. Oedometer and direct shear box tests are still the two tests commonly used in geotechnical engineering. For stability and heave problems such as slope excavation and embankment construction in shale, these testing methods may satisfy the design criteria. However, in projects involving coupled mechanical-hydraulic-chemical-thermal processes such as tunnelling, petroleum thermal recovery process, and ground water flow, analyses of these problems become complex and require constitutive laws describing the response of shale subjected to loads of different kinds. This paper presents some results of special laboratory tests to gain better understanding on the swelling behavior of shale subjected to loads of different types. Interpretation of the testing results are complex because coupled equations of compositional mass balance are required to analyze the testing results properly. Though the testing results may not quantify all the constitutive constants embedded in the governing equations, the testing results provide critical insight into the response of shale subjected to environmental changes. The objective of the paper is to develop a framework for the coupled swelling process in shale based on the results observed in the special swell tests.
