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dc.contributor.advisorDaemen, Jaaken_US
dc.contributor.authorSOUTH, DAVID LONG.
dc.creatorSOUTH, DAVID LONG.en_US
dc.date.accessioned2011-10-31T18:21:15Z
dc.date.available2011-10-31T18:21:15Z
dc.date.issued1983en_US
dc.identifier.urihttp://hdl.handle.net/10150/186836
dc.description.abstractBoreholes in the vicinity of a nuclear waste repository must be reliably sealed to prevent rapid migration of radionuclide contaminated water from the vicinity of the repository to the accessible environment. Few data currently exist regarding the effectiveness of borehole sealing. The objective of this research was to assess the performance of borehole seals under laboratory conditions, particularly with regard to varying stress fields. The approach used to evaluate borehole seals was to compare flow through a sealed borehole with flow through intact rock. Granite, basalt, and tuff were tested, using either cement or bentonite as the seal material. The main conclusions reached as a result of the experiments is that currently existing materials are capable of forming high quality seals when placed under laboratory conditions. Variation of triaxial stress state about a borehole does not significantly affect seal performance if the rock is stiffer than the seal material. Temperature/moisture variations (drying) degraded the quality of cement seals significantly. Performance partially recovered upon resaturation. A skillfully sealed borehole may reasonably be expected to be as impermeable as a fractured rock mass (subject to site-specific verification). The influence of relative seal-rock permeabilities provides insight into important seal parameters. A plug one order of magnitude greater in permeability than the rock through which it passes resulted in an increase in flow through the borehole and surrounding rock of only 1 1/2 times as compared to the undisturbed rock. Since a sealed borehole and its surrounding rock are only a small part of the total rock mass, the effect is even less pronounced. One of the simplest ways to decrease flow through a seal-rock system is to increase the length of the seal. Significant remaining questions include field emplacement techniques; field vertification of plug quality; plug performance over long time periods, particularly with respect to temperature/moisture variations and chemical stability; and radionuclide sorption capabilities. Scale effects are also important, as shafts and drifts must be sealed as well as larger diameter boreholes.
dc.language.isoenen_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © 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.en_US
dc.subjectBorehole mining.en_US
dc.subjectRadioactive waste disposal in the ground.en_US
dc.titleLABORATORY STUDIES OF FLUID FLOW THROUGH BOREHOLE SEALS.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.identifier.oclc690022936en_US
thesis.degree.grantorUniversity of Arizonaen_US
thesis.degree.leveldoctoralen_US
dc.identifier.proquest8322653en_US
thesis.degree.disciplineMining and Geological Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.namePh.D.en_US
dc.description.noteThis item was digitized from a paper original and/or a microfilm copy. If you need higher-resolution images for any content in this item, please contact us at repository@u.library.arizona.edu.
dc.description.admin-noteOriginal file replaced with corrected file July 2023.
refterms.dateFOA2018-08-16T09:08:34Z
html.description.abstractBoreholes in the vicinity of a nuclear waste repository must be reliably sealed to prevent rapid migration of radionuclide contaminated water from the vicinity of the repository to the accessible environment. Few data currently exist regarding the effectiveness of borehole sealing. The objective of this research was to assess the performance of borehole seals under laboratory conditions, particularly with regard to varying stress fields. The approach used to evaluate borehole seals was to compare flow through a sealed borehole with flow through intact rock. Granite, basalt, and tuff were tested, using either cement or bentonite as the seal material. The main conclusions reached as a result of the experiments is that currently existing materials are capable of forming high quality seals when placed under laboratory conditions. Variation of triaxial stress state about a borehole does not significantly affect seal performance if the rock is stiffer than the seal material. Temperature/moisture variations (drying) degraded the quality of cement seals significantly. Performance partially recovered upon resaturation. A skillfully sealed borehole may reasonably be expected to be as impermeable as a fractured rock mass (subject to site-specific verification). The influence of relative seal-rock permeabilities provides insight into important seal parameters. A plug one order of magnitude greater in permeability than the rock through which it passes resulted in an increase in flow through the borehole and surrounding rock of only 1 1/2 times as compared to the undisturbed rock. Since a sealed borehole and its surrounding rock are only a small part of the total rock mass, the effect is even less pronounced. One of the simplest ways to decrease flow through a seal-rock system is to increase the length of the seal. Significant remaining questions include field emplacement techniques; field vertification of plug quality; plug performance over long time periods, particularly with respect to temperature/moisture variations and chemical stability; and radionuclide sorption capabilities. Scale effects are also important, as shafts and drifts must be sealed as well as larger diameter boreholes.


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