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Time and scale effects in laboratory permeability testing of compacted clay soil

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dc.contributor.authorJaved, Farhat, author
dc.contributor.authorShackelford, Charles D., advisor
dc.contributor.authorJameson, Donald A., advisor
dc.contributor.authorDoehring, Donald O., committee member
dc.contributor.authorAbt, Steven R., committee member
dc.date.accessioned2018-10-22T14:21:19Z
dc.date.available2018-10-22T14:21:19Z
dc.date.issued1989
dc.description.abstractPermeability (hydraulic conductivity) testing of clays in the laboratory typically requires a significant amount of time. It is hypothesized that the time required for clay permeability test can be reduced substantially through a statistical modelling technique known as "time series analysis". In order to test this hypothesis, permeability tests were performed on compacted samples of a silty clay soil in a standard Proctor mold (9.4 x 10-4 m3). The soil was separated into five different fractions representing five ranges in precompaction clod sizes. Constant-head permeability tests were performed on each of these five fractions. Tests were replicated five times for the time series analysis. The results of analysis indicate that time series modelling can significantly reduce statistical error associated with permeability data. It is demonstrated that the time required for clay permeability test can be reduced appreciably through time series modelling. Permeability tests also were performed on four soil fractions in a large-scale (0.914 m x 0.914 m x 0.457 m) double-ring, rigid-wall permeameter. The results of small-scale (Proctor mold) permeability tests indicate that the soil permeability does not vary much with a change in the precompaction clod size. Presence of large clods (> 25 mm), however, may result in side-wall leakage. The large-scale tests indicated that permeability is strongly related to the precompaction clod sizes. Permeability of the soil increased more than two orders-of-magnitude as the maximum precompaction clod size increased from 4.75 mm to 75 mm. Comparison of the results from the small-scale and the large-scale tests indicated that, for all soil fractions, the large-scale permeability was higher by more than an order-of-magnitude. As a result, there appears to be a scale-effect associated with laboratory permeability testing. This scale effect is more significant when soil contains considerable quantity of clods that are large relative to the size of permeameter. These results imply that the large-scale test is more capable of accounting for the hydraulic defects resulting from large clods. A more realistic evaluation of the field permeability of a compacted clay, therefore, may be possible in the laboratory if the permeameter is fairly large relative to the maximum precompaction size of clods present under field conditions.
dc.format.mediumdoctoral dissertations
dc.identifier.urihttps://hdl.handle.net/10217/192614
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relationCatalog record number (MMS ID): 991016619479703361
dc.relationS592.367.J37 1989
dc.relation.ispartof1980-1999
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.subject.lcshClay soils -- Testing
dc.titleTime and scale effects in laboratory permeability testing of compacted clay soil
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineCivil Engineering
thesis.degree.grantorColorado State University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (Ph.D.)

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