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Permeability (earth sciences)

About: Permeability (earth sciences) is a research topic. Over the lifetime, 15424 publications have been published within this topic receiving 288535 citations.


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01 Jan 2005
TL;DR: In this paper, the effect of crack width and crack frequency upon the durability of reinforced mortar, quantified by water permeability, was examined and compared with a small number of large cracks over a large number of closely spaced microcracks.
Abstract: Cracking is one of the most severe problems facing the concrete industry worldwide. Of critical importance is the drastic decline of durability associated with these cracks, and the resulting cost of repair or replacement of concrete structures. This research examines the effect of crack width and crack frequency upon the durability of reinforced mortar, quantified by water permeability. Crack widths tested range from 0mm (for uncracked mortar) up to 2.7mm. In addition to mortar, the durability performance of Engineered Cementitious Composites, or ECC, are also investigated in the cracked state. This high performance fiber reinforced cementitious composite exhibits closely spaced microcracks with inherently tight crack widths, typically less than 80 micron, even when strained up to 5% in uniaxial tension. The advantages of closely spaced microcracks over a small number of large cracks are investigated and discussed. Results show that even with a large number of closely spaced microcracks, the inherently small crack width of ECC material exhibits a water permeability close to that of uncracked concrete when strained up to 1.5% in uniaxial tension.

103 citations

Journal ArticleDOI
TL;DR: In this paper, water seepage in thick unsaturated zones in fractured rocks of low matrix permeability cannot be understood by considering spatial and temporal averages, and the authors suggest that most such seepages proceeds in an unsteady, episodic manner in localized preferential pathways, where water flows relatively freely in networks of interconnected fractures in the presence of strong suction pressures from an unsaturated rock matrix.
Abstract: The theme developed in this paper is that water seepage in thick unsaturated zones in fractured rocks of low matrix permeability cannot be understood by considering spatial and temporal averages We suggest that most such seepage proceeds in an unsteady, episodic manner in localized preferential pathways Mechanisms are proposed and explored which permit water to flow relatively freely in networks of interconnected fractures in the presence of strong suction pressures from an unsaturated rock matrix Imbibition into the rock matrix is reduced by limited wetted area, the episodic nature of flow, and possibly also by the presence of mineral coatings of low permeability on the fracture walls These effects and conditions combine to limit total imbibition rates to values less than saturated matrix hydraulic conductivity, leaving the rock matrix in partially saturated conditions even as water is flowing freely in portions of the fracture network The proposed conceptual model is elaborated and substantiated with analytical estimates and numerical simulation studies Mechanisms are demonstrated that can funnel distributed seepage into spatially localized preferential paths Subsequent horizontal broadening from dispersive mechanisms is found to be a slow process for fractures of high intrinsic permeability The presence of an unsaturated rock matrix provides constraints on fracture-matrix interface areas for imbibition and on the frequency of episodic deep seepage events Further studies are needed to test the proposed model

102 citations

Journal ArticleDOI
TL;DR: In this paper, a micromechanics-based damage model is proposed for the description of anisotropic damage and the normal opening of microcracks generated by the frictional sliding due to the roughness of crack surface is also considered.

102 citations

Journal ArticleDOI
TL;DR: In this article, the authors examined several possible explanations for why some gels reduce water permeability more than oil permeability and found that the disproportionate reduction is not caused by gravity or lubrication effects.
Abstract: A capacity to reduce water permeability much more than oil permeability is critical to the success of gel treatments in production wells if zones cannot be isolated during gel placement. Although several researchers have reported polymers and gels that provide this disproportionate permeability reduction, the explanation for the phenomenon was unclear. In this paper, the authors examine several possible explanations for why some gels reduce water permeability more than oil permeability. Their experimental results indicate the disproportionate permeability reduction is not caused by gravity or lubrication effects. Results also indicate that gel shrinking and swelling are unlikely to be responsible for the phenomenon. Although wettability may play a role in the disproportionate permeability reduction, it does not appear to be the root cause for water permeability being reduced more than oil permeability. Results from an experiment with an oil-based gel suggest that segregation of oil and water pathways through a porous medium (on a microscopic scale) may play the dominant role in the disproportionate permeability reduction. However, additional work will be required to verify this concept.

102 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202242
2021833
2020901
2019916
2018847
2017849