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Regional geology, groundwater flow systems and slope stabilityHodge, Robert A.L. January 1976 (has links)
The purpose of this thesis is to show, using computer simulation of flow systems in a variety of hypothetical slopes, how different geological environments affect the groundwater flow regime, which in turn is fundamental
to the stability of a slope. Galerkin's method is used to derive a finite element program to model two dimensional, saturated, steady state flow through anisotropic and heterogeneous rigid porous media.
An understanding of the regional geology is required in order to understand
the regional flow system. The following points are illustrated.
a. In anisotropic media, the most adverse groundwater condition for slope stability occurs when the major axis of conductivity
lies down the dip of the slope.
b. Depending on their characteristics, faults, contacts and dykes can be either detrimental or favourable in their effect
on the flow system. Careful field investigation is required to establish that effect.
c. Deep weathering commonly causes a confining zone of low conductivity, a situation very detrimental to stability.
d. Stress relief fractures on valley walls can adversely influence
the effect of groundwater on stability.
e. A regional aquifer can cause high pore pressure development beneath a valley.
f. Fluctuations in the regional groundwater system can cause instability in Pleistocene terraces.
g. The presence of an underlying less conductive zone or unit
can have an adverse effect on the flow system. Conductivity contrasts of less than two orders of magnitude can cause pore pressure development critical to stability. Three other points are demonstrated which have direct application to slope stability analysis and control.
1. The pressure head distribution on rock wedges can be nonlinear
rather than the commonly assumed linear distribution.
2. The introduction of a reservoir at the toe of a slope can influence the groundwater regime well above the reservoir surface; even a low reservoir can cause, the change required to cause instability.
3. Piezometric measurements and drainage systems must penetrate through any less conductive unit that might be acting as a slide plane. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate
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Active layer depths and suprapermafrost groundwater in a small subarctic catchment, Schefferville, QuebecLewis, Jonathan S. January 1977 (has links)
No description available.
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Analytical and numerical analysis of LNAPL migration and LNAPL thickness estimation in unconfined aquifersLiao, Boshu 05 1900 (has links)
No description available.
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A stochastic approach to a groundwater flow model of southern Honey Lake Valley in Lassen County, CA and Washoe County, NVHumphrey, Steven. January 2008 (has links)
Thesis (M.S.)--University of Nevada, Reno, 2008. / "December, 2008." Includes bibliographical references (leaves 85-89). Online version available on the World Wide Web.
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Delineating contributing areas for karst springs using NEXRAD data and cross-correlation analysisBudge, Trevor Jones, January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.
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Theoretical and field studies of fluid flow in fractured rocksHsieh, P. A.(Paul A.) January 1983 (has links)
A comprehensive methodology of hydraulic testing in fractured rocks is presented. The methodology utilizes geological and geophysical information as background. It consists of conventional single-hole packer tests in conjection with a newly developed cross-hole packer test. The cross-hole method involves injecting fluid into a packed-off interval in one borehole and monitoring hydraulic head variations in packed-off intervals in neighboring boreholes. Borehole orientation is unrelated to the principal hydraulic conductivity directions which, therefore, need not be known a priori. The method yields complete information about the directional nature of hydraulic conductivity in three dimensions on a scale comparable to the distance between the test boreholes. In addition to providing all six components of the hydraulic conductivity tensor, the cross-hole method also yields the specific storage of the fractured rock mass. While the theory behind this method treats the rock as a homogeneous, anisotropic, porous medium, the test provides detailed information about the degree to which such assumptions may actually be vaild in the field. The method may also be useful as a tool for detecting, in the vicinity of the test area, major fractures or faults that have not been intercepted by boreholes. Preliminary results from a granitic site near Oracle in southern Arizona are presented together with details of the instrumentation designed and constructed specifically for that site.
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Simulation Of Groundwater Flow In The Rincon Valley Area And Mesilla Basin, New Mexico And TexasWeeden, A. Curtis,Jr., Maddock, Thomas, III 30 September 1999 (has links)
A groundwater flow model was constructed for the Rincon Valley area and Mesilla
Basin. The system is dominated by the complex interaction of the Rio Grande, canals, laterals,
and drains with groundwater pumping. The primary purpose of the model was to aid the New
Mexico -Texas Water Commission in assessing options for water resources development in the
Lower Rio Grand Basin from Caballo Reservoir in New Mexico to El Paso, Texas. One such
assessment was to evaluate the effect of secondary irrigation releases from Caballo Reservoir on
the water budget. In addition, the model will eventually be linked to a surface water model
(BESTSM) being utilized by the New Mexico -Texas Water Commission to evaluate water
supply alternatives for El Paso, Texas.
Stress periods were specified on a seasonal basis, a primary irrigation season from March
through October and a secondary irrigation season from November through February. Analysis
of model output indicates that groundwater pumping decreases Rio Grande flows, secondary
irrigation season releases do not alter the water budget significantly, and that recharge and
discharge from aquifer storage are strongly related to the season.
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A laboratory assessment of flow characteristics and permeability of fractures in rockRyan, Thomas Michael, 1963- January 1987 (has links)
Intact and fractured rock samples were studied in the laboratory in order to understand more fully the mechanism of closure of fractures subjected to high confining stresses and the resultant effect on specimen permeability. Confining stresses applied to the specimens ranged from 3.0 to 20.0 MPa, and the closure of fractures was observed by monitoring the change in the hydraulic conductivity of the specimens. Test results suggest that some resealing may occur due to crushing and realignment of mineral grains along a fracture surface. The closure of fractures is dependent upon the strength of the rock mass, the physical nature of the fracture, and the fluid pressure present in the fracture. Fracture closure is highly time dependent, and a number of nonlinear pressure flow relationships have been identified. These deviations are thought to represent two fundamentally different processes, the most important of which are turbulence in the flow and fracture expansion.
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Analysis of Borehole Infiltration Tests Above the Water TableStephens, Daniel Bruce, Neuman, Shlomo P. 03 1900 (has links)
Project Completion Report OWRT Project A- 076 -ARIZ
The work upon which this publication is based was
supported in part by the United States Department
of the Interior as authorized under the Water
Research Act of 1964, as amended. / Constant head borehole infiltration tests are widely used for the in
situ evaluation of saturated hydraulic conductivities of unsaturated soils
above the water table. The formulae employed in analyzing the results of
such tests disregard the fact that some of the infiltrating water may flow
under unsaturated conditions. Instead, these formulae are based on various
approximations of the classical free surface theory which treats the flow
region as if it were fully saturated and enclosed within a distinct envelope,
the so- called "free surface." A finite element model capable of solving
free surface problems is used to examine the mathematical accuracy of the
borehole infiltration formulae. The results show that in the hypothetical
case where unsaturated flow does not exist, the approximate formulae are
reasonably accurate within a practical range of borehole conditions. To
see what happens under conditions closer to those actually encountered in
the field, the effect of unsaturated flow on borehole infiltration is investigated
by means of two different numerical models: A mixed explicit -
implicit finite element model, and a mixed explicit -implicit integrated
finite difference model. Both of these models give nearly identical results;
however, the integrated finite difference model is considerably faster than
the finite element model. The relatively low computational efficiency of
the finite element scheme is attributed to the large humber of operations
required in order to reevaluate the conductivity (stiffness) matrix at each
iteration in this highly nonlinear saturated -unsaturated flow problem. The
saturated -unsaturated analysis demonstrates that the classical free surface
approach provides a distorted picture of the flow pattern in the soil. Contrary to what one would expect on the basis of this theory, only a
finite region of the soil in the immediate vicinity of the borehole is
saturated, whereas a significant percentage of the flow takes place under
unsaturated conditions. As a consequence of disregarding unsaturated flow,
the available formulae may underestimate the saturated hydraulic conductivity
of fine grained soils by a factor of two, three, or more. Our
saturated -unsaturated analysis leads to an improved design of borehole infiltration
tests and a more accurate method for interpreting the results of
such tests. The analysis also shows how one can predict the steady state
rate of infiltration as well as the saturated hydraulic conductivity from
data collected during the early transient period of the test.
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Groundwater movement and subsurface air flow induced by land reclamation and tidal fluctuation in coastal aquifersGuo, Haipeng, 郭海朋 January 2008 (has links)
published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy
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