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An Fourier Series solution is presented that describes the simultaneous, one-dimensional, vertical flow of heat and ground water in homogeneous, porous media beneath streams. Use of this analytical solution provides an indirect method of determining vertical flow rates and the effective vertical hydraulic connection between sediments and overlying streams. The method consists of varying the Darcy velocity in the solution until the temperature profiles predicted by the solution match those measured in the field. The method was applied at three field sites in Central Massachusetts. At the first site, which is underlain by lacustrine clay, the vertical flow rate through the clay was determined to be less than 5x10⁻⁷ cm/s and the vertical hydraulic conductivity was less than 0.08 cm/s. The vertical flow rate through mixed sand and gravel underlying the second site equaled 7.5x10⁻⁶ cm/s and vertical hydraulic conductivities of sediments underlying the site ranged from 3.8x10⁻⁴ to 3.1x10⁻³ cm/s. The vertical flow rate through mixed sand and gravel underlying the third site ranged from 3x10⁻⁵ to 7x10⁻⁵ cm/s and vertical hydraulic conductivities of sediments underlying the site ranged from 1x10⁻³ to 4x10⁻³ cm/s. The simultaneous flow of heat and ground water in sediments beneath streams may be more complex than that assumed for the Fourier Series solution. The additional complexity may be partially attributable to two factors: the presence of horizontal ground-water flow, and the presence of thermal conditions near the stream that differ from conditions in the stream itself. The effects of that these two factors have on thermal regimes in sediments beneath streams were investigated using numerical simulations. Results indicate, for example, that under conditions of no horizontal ground-water flow, thermal conditions near the stream can affect temperatures in sediments beneath the stream as far as 900 cm from the stream bank. For horizontal flow rates greater than about 1x10⁻⁴ cm/s, thermal conditions near the stream can affect temperatures in sediments beneath the stream as far as 1500 cm from the stream bank. The method of determining flow rates and hydraulic connection has been applied to stream-aquifer systems. However, the method also may have application in other hydrologic settings. Two such applications might be to determine flow rates to and from lakes and rates of recharge to aquifers.

The self-potential method responds to the electrokinetic phenomenon of streaming potential and has been applied in hydrogeologic and engineering investigations to aid in the evaluation of subsurface hydraulic conditions. Of specific interest is the application of the method to embankment dam seepage monitoring and detection. This demands a quantitative interpretation of seepage conditions from the geophysical data. To enable the study of variably saturated flow problems of complicated geometry, a three-dimensional finite volume algorithm is developed to evaluate the self-potential distribution resulting from subsurface fluid flow. The algorithm explicitly calculates the distribution of streaming current sources and solves for the self-potential given a model of hydraulic head and prescribed distributions of the streaming current cross-coupling conductivity and electrical resistivity. A new laboratory apparatus is developed to measure the streaming potential coupling coefficient and resistivity in unconsolidated soil samples. Measuring both of these parameters on the same sample under the same conditions enables us to properly characterize the streaming current cross-coupling conductivity coefficient. I present the results of a laboratory investigation to study the influence of soil and fluid parameters on the cross-coupling coefficient, and characterize this property for representative well-graded embankment soils. The streaming potential signals associated with preferential seepage through the core of a synthetic embankment dam model are studied using the forward modelling algorithm and measured electrical properties to assess the sensitivity of the self-potential method in detecting internal erosion. Maximum self-potential anomalies are shown to be linked to large localized hydraulic gradients that develop in response to piping, prior to any detectable increase in seepage flow through the dam. A linear inversion algorithm is developed to evaluate the three-dimensional distribution of hydraulic head from self-potential data, given a known distribution of the cross-coupling coefficient and electrical resistivity. The inverse problem is solved by minimizing an objective function, which consists of a data misfit that accounts for measurement error and a model objective function that incorporates a priori information. The algorithm is suitable for saturated flow problems or where the position of the phreatic surface is known. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Internal instability of a widely graded cohesionless soil refers to a phenomenon in which its finer particles migrate within the void network of its coarser particles, as a result of seepage flow. Onset of internal instability of a soil is governed by a combination of geometric and hydromechanical constraints. Much concern exists for embankment dams and levees built using soils with a potential for internal instability. Migration of finer particles to a boundary where they can exit, by washing out, may cause erosion or piping failure and, occasionally, induce collapse of these soil structures. There is a need, in professional practice, to better understand the phenomenon and to develop improved methods to evaluate the susceptibility of a soil. A series of permeameter tests was performed on six widely-graded cohesionless materials. The objectives are to assess the geometric indices proposed for evaluation of susceptibility, and examine hydromechanical factors influence the onset of internal instability. A modified slurry mixing technique, with discrete deposition, was found satisfactory for reconstitution of the homogeneous saturated test specimens. The onset of internal instability was founded to be triggered by a combination of effective stress and hydraulic gradient. The finding yields a hydromechanical envelope, unique for a particular gradation shape, at which internal instability initiated. Three commonly used geometric criteria were comprehensively evaluated with reference to these experimental data and also a database compiled from the literature. The relative conservatism of each criterion was examined and a modified semi-empirical geometric rule then proposed based on the capillary tube model. A theoretical framework for plotting the hydromechanical envelope was established based on an extension of the α concept of Skempton and Brogan, and subsequently verified by test data. Finally, a novel unified approach was proposed to assess the onset of internal instability, based on combining geometric and hydromechanical indices of a soil. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 121-123. / by Gary E.B. Choot. / M.S.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21748号 / 工博第4565号 / 新制||工||1712(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 大津 宏康, 准教授 PIPATPONGSA Thirapong, 教授 三村 衛 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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京都大学 / 新制・課程博士 / 博士(工学) / 甲第23476号 / 工博第4888号 / 新制||工||1764(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 渦岡 良介, 教授 三村 衛, 教授 肥後 陽介 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23485号 / 工博第4897号 / 新制||工||1765(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 渦岡 良介, 教授 肥後 陽介, 准教授 PIPATPONGSA Thirapong / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Levees are a significant part of the United States flood protection infrastructure. It is estimated that over 100,000 miles of levees exist in the United States. Most of these levees were designed many years ago to protect farmland and rural areas. As growth continues in the United States, many of these levees are now protecting homes and other important structures. The American Society of Civil Engineers gave the levees in the United States a grade of D- in 2009. To bring flood protection up to modern standards there requires adequate methods of evaluating levees with respect to seepage, erosion, piping and slope instability. Transient seepage analyses provide an effective method of evaluating seepage through levees and its potentially destabilizing effects. Floods against levees usually last for days or weeks. In response to a flood, pore pressures within the levee will change from negative (suction) to positive as the phreatic surface progresses through the levee. These changes can be calculated by finite element transient seepage analyses. In order for the transient seepage analysis to be valid, appropriate soil properties and initial conditions must be used. The research investigation described here provides simple and practical methods for estimating the initial conditions and soil properties required for transient seepage analyses, and illustrates their use through a number of examples. / Ph. D.