Infiltration of a Liquid Front in an Unsaturated, Fractured Porous Medium

We consider liquid infiltrating by gravity flow into a system of parallel, regularly spaced fractures in an unsaturated porous medium. The position of the fracture liquid front as a function of time, under some simplifying assumptions, is shown to obey a nonlinear integrodifferential equation. Appro...

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Bibliographic Details
Published in:Water resources research 1991-08, Vol.27 (8), p.2099-2112
Main Authors: Nitao, John J., Buscheck, Thomas A.
Format: Article
Language:English
Subjects:
052002 - Nuclear Fuels- Waste Disposal & Storage
540220 - Environment, Terrestrial- Chemicals Monitoring & Transport- (1990-)
AQUIFERS
ENVIRONMENTAL SCIENCES
FLOW MODELS
FLUID FLOW
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GROUND WATER
HYDROGEN COMPOUNDS
HYDROLOGY
MANAGEMENT
MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
MATERIALS
MATHEMATICAL MODELS
NUCLEAR FACILITIES
OXYGEN COMPOUNDS
POROUS MATERIALS
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE FACILITIES
RADIOACTIVE WASTE MANAGEMENT
RADIOACTIVE WASTE STORAGE
RADIOACTIVE WASTES
RISK ASSESSMENT
SITE CHARACTERIZATION
SOILS
STORAGE
TWO-DIMENSIONAL CALCULATIONS
WASTE MANAGEMENT
WASTE STORAGE
WASTES
WATER
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Summary:We consider liquid infiltrating by gravity flow into a system of parallel, regularly spaced fractures in an unsaturated porous medium. The position of the fracture liquid front as a function of time, under some simplifying assumptions, is shown to obey a nonlinear integrodifferential equation. Approximate analytic solutions are developed, showing that the movement of the liquid front exhibits three major flow periods: (1) at early time, the frontal position is determined by the fracture inlet boundary condition and the gravity‐driven flow behavior of the fracture with negligible influence by the matrix; (2) at intermediate time, matrix imbibition retards the frontal advance against the pull of gravity; (3) at late time, the matrix approaches saturation and the frontal velocity approaches a limiting value. A two‐dimensional numerical model is used to confirm the approximate solutions. Implications of the model for nuclear waste storage are discussed. The analysis is applicable not only to fractured rock but also to lateral infiltration into coarse‐grained sediments lying between layers of fine‐grained soil.
ISSN:0043-1397
1944-7973
DOI:10.1029/91WR01369