Show simple item record

dc.contributor.advisorChairperson, Graduate Committee: Edward E. Adamsen
dc.contributor.authorJepsen, Steven Michaelen
dc.coverage.spatialAntarcticaen
dc.date.accessioned2013-06-25T18:41:56Z
dc.date.available2013-06-25T18:41:56Z
dc.date.issued2005en
dc.identifier.urihttps://scholarworks.montana.edu/xmlui/handle/1/1560en
dc.description.abstractThe relative importance of nonhydrostatic stress and lattice-rejected impurities on the phase equilibrium of intergranular liquid water in the Vostok accretion ice, Eastern Antarctica, was examined in this study. In addition, experiments were conducted to examine the influence of intergranular water in ice on the permeability of a Light Non-Aqueous Phase Liquid (LNAPL) hydrocarbon. Sub-grain scale stresses in the Vostok accretion ice were simulated with anisotropic elastic and elastocreep finite element (FE) models and compared to X-ray dislocation topographs. The phase equilibrium conditions were solved separately using stresses simulated by the FE models and ice chemistry data obtained from literature. The permeability of ice to JP-8 aviation fuel, the primary component of drilling fluid used in the Vostok borehole, was tested in three Fuel-Ice (FI) Experiments on unfractured ice in dark conditions near the melting point. The shear stresses simulated by the elastic FE model indicated plastic deformation, via basal glide, in the Vostok accretion ice. This finding was supported by observed dislocation densities exceeding 107 m-2, with higher values reported in literature. The elasto-creep FE model indicated onset of intergranular melt, at scales ₃ 1% the crystal size, in the lower few meters of the westernmost accretion ice. Model predictions of strain rate and internal melt were in reasonable agreement with literature data on polycrystalline ice. Based on an impurity model, which assumed hydrostatic stress, millimeter-size intergranular water veins were predicted in the lower few dekameters of accretion ice. The FI Experiments indicated that these water veins in ice provide conduits for rapid (> 16 cm hr-1) infiltration of JP-8 fuel in dark conditions near the melting point. This transport mechanism, referred to as fuel-tunneling, involved the formation of intergranular tubes, 1-2 mm in diameter, that were absent from experiments using ice grown from distilled water. It was concluded that intergranular water veins in ice near the melting point provide tunneling conduits for LNAPL hydrocarbons. This fuel-tunneling may be accelerated in the basal-most part of the accretion ice due to intergranular melting from both deviatoric stress and mechanical anisotropy. These results have implications for environmentally-clean penetration methods of subglacial lake exploration.en
dc.language.isoenen
dc.publisherMontana State University - Bozeman, College of Engineeringen
dc.subject.lcshIcing (Meteorology)en
dc.subject.lcshPermeabilityen
dc.subject.lcshAnisotropyen
dc.titleIntergranular water and permeability of the Lake Vostok accretion ice, Eastern Antarcticaen
dc.typeDissertationen
dc.rights.holderCopyright 2005 by Steven Michael Jepsenen
thesis.catalog.ckey1175068en
thesis.degree.committeemembersMembers, Graduate Committee: Joseph Seymour; Ladean McKittrick; Robert Oakbergen
thesis.degree.departmentCivil Engineering.en
thesis.degree.genreDissertationen
thesis.degree.namePhDen
thesis.format.extentfirstpage1en
thesis.format.extentlastpage157en
mus.relation.departmentCivil Engineering.en_US


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record


MSU uses DSpace software, copyright © 2002-2017  Duraspace. For library collections that are not accessible, we are committed to providing reasonable accommodations and timely access to users with disabilities. For assistance, please submit an accessibility request for library material.