Gas permeability changes in rock salt during deformation.

A laboratory, field and numerical study of the changes in gas permeability which rock salt experiences during deformation is given. The laboratory tests involves gas permeability and porosity measurements coincident with hydrostatic and triaxial quasi-static, stress-rate controlled compression tests. The permeability and porosity of the as-received samples decrease significantly as a result of hydrostatic loading. These changes are largely irreversible, and are believed to "heal" or return the rock to a condition comparable to its undisturbed state. Deviatoric loading induces a dramatic change in pore structure. The permeability can increase more than 5 orders of magnitude over the initial (healed) state as the samples are loaded. The gas permeability changes are consistent with flow paths initially developing along the grain boundaries and then along axial secondary tensile cracks. The results from two sets of in situ gas permeability measurements from the underground workings of the WIPP Facility are given. The results consistently indicate that there is no measurable gas permeability prior to disturbing the rock by excavation. In the immediate vicinity of an excavation, the gas permeability can be 5 orders of magnitude greater than the undisturbed permeability. A numerical procedure to predict the in situ permeability is developed based on the results of the laboratory tests. The stress and strain fields surrounding excavations in rock salt, predicted with an elastoplastic model, are used in a model of gas permeability based on the equivalent channel model. The zone of the gas permeable rock is predicted well, but the magnitude of the gas permeability is underpredicted very near excavations. The gas permeability which develops in situ is principally a result of flow along dilated grain boundaries.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Mining and Geological Engineering

Grantor dc:publisher

The University of Arizona.

Year dc:date.issued

1990

Author dc:creator

• Stormont, John Charles.

Advisor dc:contributor.advisor

• Daemen, J.

Committee members dc:contributor.committeemember

• Farmer, I.
• Harpalani, S.
• Desai, C.
• Kiousis, P.

Statement dc:rights

• Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/10150/185159

OAI identifier oai:identifier

oai:repository.arizona.edu:10150/185159