Persistent Link:
http://hdl.handle.net/10150/186655
Title:
Experimental assessment of borehole plug stability.
Author:
Cetintas, Arif.
Issue Date:
1994
Publisher:
The University of Arizona.
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.
Abstract:
This study presents the results of laboratory-scale experimental, analytical and numerical investigations on the sealing performance of crushed tuff concrete plugs in the welded brown unit of the Apache Leap tuff. Included are experimental studies of the bond strength, of the hydraulic conductivity, and of geochemical interactions between cement and the crushed tuff aggregate. The bond strength is measured by means of a total of 37 push-out tests on concrete borehole seals emplaced in hollow cylinders of welded tuff. Lateral stress is applied to 17 rock cylinders during push-out testing. Results are presented of an extensive finite element analysis of the stress distribution during push-out testing. Particular attention is paid to tensile zones in the plug and the host rock. Geochemical interaction analysis includes tests for alkali-silica reaction between the cement and crushed tuff aggregate. ASTM standard tests for the determination of alkali-silica reactivity of aggregates, in addition to uranyl acetate staining test have been performed. Hydraulic conductivity tests include constant head tests on plugged tuff cylinders and falling head tests on fractures induced by push-out testing along the plug/rock interface. The falling head tests have been conducted after the plugs were left to dry for two years in a laboratory environment. The main conclusion from the analysis of push-out tests is that high tensile stresses develop in plugs with a modulus ratio of 1.09 and length-to-diameter ratio of 1. Application of lateral stress to rock cylinders reduces the volume of plug under tension. Results of tests on alkali-silica reactivity indicated that Apache Leap tuff reacts with the alkalies in cement and expand. Replacement of cement 33% by weight with low-calcium Class F fly ash reduces the expansion 50%. Hydraulic conductivity of concrete plug and plug/rock interface interpreted from constant head tests is in the range of 10⁻¹⁰ cm/s. Hydraulic conductivity of fractures along the interface decreased from 10⁻² cm/s to 10⁻⁶ cm/s upon wetting of the concrete, due to the expansion of the cement.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Dissertations, Academic.; Mining engineering.; Environmental geotechnology.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Mining and Geological Engineering; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Kemeny, John M.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleExperimental assessment of borehole plug stability.en_US
dc.creatorCetintas, Arif.en_US
dc.contributor.authorCetintas, Arif.en_US
dc.date.issued1994en_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.description.abstractThis study presents the results of laboratory-scale experimental, analytical and numerical investigations on the sealing performance of crushed tuff concrete plugs in the welded brown unit of the Apache Leap tuff. Included are experimental studies of the bond strength, of the hydraulic conductivity, and of geochemical interactions between cement and the crushed tuff aggregate. The bond strength is measured by means of a total of 37 push-out tests on concrete borehole seals emplaced in hollow cylinders of welded tuff. Lateral stress is applied to 17 rock cylinders during push-out testing. Results are presented of an extensive finite element analysis of the stress distribution during push-out testing. Particular attention is paid to tensile zones in the plug and the host rock. Geochemical interaction analysis includes tests for alkali-silica reaction between the cement and crushed tuff aggregate. ASTM standard tests for the determination of alkali-silica reactivity of aggregates, in addition to uranyl acetate staining test have been performed. Hydraulic conductivity tests include constant head tests on plugged tuff cylinders and falling head tests on fractures induced by push-out testing along the plug/rock interface. The falling head tests have been conducted after the plugs were left to dry for two years in a laboratory environment. The main conclusion from the analysis of push-out tests is that high tensile stresses develop in plugs with a modulus ratio of 1.09 and length-to-diameter ratio of 1. Application of lateral stress to rock cylinders reduces the volume of plug under tension. Results of tests on alkali-silica reactivity indicated that Apache Leap tuff reacts with the alkalies in cement and expand. Replacement of cement 33% by weight with low-calcium Class F fly ash reduces the expansion 50%. Hydraulic conductivity of concrete plug and plug/rock interface interpreted from constant head tests is in the range of 10⁻¹⁰ cm/s. Hydraulic conductivity of fractures along the interface decreased from 10⁻² cm/s to 10⁻⁶ cm/s upon wetting of the concrete, due to the expansion of the cement.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectDissertations, Academic.en_US
dc.subjectMining engineering.en_US
dc.subjectEnvironmental geotechnology.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineMining and Geological Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairKemeny, John M.en_US
dc.contributor.committeememberDaemen, Jaak J.K.en_US
dc.contributor.committeememberHarpalani, Satyaen_US
dc.contributor.committeememberKiousis, Panosen_US
dc.identifier.proquest9426217en_US
dc.identifier.oclc722879272en_US
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