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No description available.

No description available.

A capillary barrier develops and restricts water flow when two porous materials with dissimilar pore structures (e.g., a coarse-grained soil overlain by a fine-grained soil) are in contact with one another. This is due to a difference in the unsaturated hydraulic conductivity of the two materials at a given suction. Geotextiles are utilized in a variety of civil engineering applications and have a pore structure similar to that of a coarse-grained soil. This can be problematic in unsaturated soil as the capillary barrier caused by the geotextile may instigate undesirable moisture buildup in the overlying soil and undermine any benefit provided by the geotextile. Various versions of a new geotextile have been manufactured to help dissipate a capillary barrier by "wicking" or laterally draining excess moisture away from the soil. Additionally, nonwoven blends of the unique wicking fiber combined with standard polymeric fibers are tested to assess their ability to minimize the development of a geotextile capillary barrier and not cause additional moisture accumulation in the first place. The unsaturated properties of both woven and nonwoven configurations of these wicking geotextiles were investigated as part of a comprehensive an experimental testing program. The testing program includes small soil column infiltration tests to assess geotextile capillary barrier performance with moisture monitored by time domain reflectometers and capacitance probes. Also, modified hanging column tests were conducted to define the hydraulic properties of the geotextiles in the form of water retention curves. Finally, a microscopy study, involving both optical and scanning electron microscopes, was conducted to observe the wicking behavior of the geotextiles at a micro-scale level. Test results illustrate the enhanced lateral drainage and reduced moisture accumulation of the wicking geotextiles when compared to regular geotextiles. Additionally, the woven version of the wicking geotextile has the potential to perform the functions of separation, filtration, protection, reinforcement, and drainage. All of these functions in a single geosynthetic product could lead to significant cost savings compared to the use of separate products to perform each one of the various functions. / text

Thesis (M.S.) in Civil Engineering--University of Maine, 2007. / Includes vita. Includes bibliographical references (leaves 191-197).

Thesis (Ph.D.)--Drexel University, 2010. / Includes abstract and vita. Includes bibliographical references (leaves 155-159).

Thesis (M.C.E.)--University of Delaware, 2009. / Principal faculty advisors: Dov Leshchinsky and Christopher L. Meehan, Dept. of Civil & Environmental Engineering. Includes bibliographical references.

The clogging of fine-porosity geotextiles by soil particles is considered to be a problem in applications of these fabrics to filtering of municipal and industrial effluents. However, the clogging phenomenon can be an advantage for certain purposes, such as the creation of near-watertight membranes for sealing manure holding tanks. The conceived advantages of non-woven needle-punctured geotextiles are that they are less expensive due to lower material quantity, they are more resistant to tensile stresses compared to impermeable plastics and concrete, and they are easily installed. This thesis describes experimental work on the permeability and clogging characteristics of a Non-woven Polyester Geotextile with three different porosities (13.4, 19.5 and 26.0mum) but the same hydraulic conductivity (Kw = 10-5 m/s), when subjected to different heads of cattle slurry at 1, 2 and 4% total solids (TS) concentrations. The resulting infiltration rates were used to establish the effect of geotextile pore size and manure TS on geotextile sealing and to find the location of the seal, whether at the surface or within the geotextile. After 100 days of experimentation, the lowest infiltration rate of 1.1 L/m2/d was reached with the 13.4mum geotextile. Manure TS had a significant effect on the sealing and at least 4% TS was required to minimize the geotextile's infiltration rate. Clogging occurred within the pores, suggesting that the seal remains even after removing the manure. / This advantage can be translated into economic benefit when fun cost comparisons with sealing liners such as geomembranes and concrete are undertaken. / This research also reviews and analyzes the physical, chemical and biological processes leading to clogging of geotextiles as well as a cost-benefit comparison with the other sealing materials. The analysis concludes that clogged geotextiles are a wise choice for Canadian livestock producers.

Soils which were known to have caused sedimentation problems in drain pipes were used in the investigations. Different envelope combinations such as soil-fabric, soil-gravel and soil-sand-fabric were evaluated. Nine 100 mm diameter, 250 mm high permeameters were used to determine the functioning of envelope materials and to improve the criteria for testing of envelope materials. To obtain a clear indication of success/failure of an envelope, a wide range of hydraulic gradients and different thicknesses of soils and envelopes were used. The most effective thicknesses were, 5 cm of soil with fabrics and 2.5 cm of soil plus 7.5 cm of gravel for gravel envelopes. / All the fabrics were successful in retaining the soil particles. No clogging was observed and higher flow rates were measured in fabrics having 2 to 3 mm thicknesses with openings O$ sb{95}$ finer than 100 $ mu$m. / SCS criteria (1988) with the following modifications: $ rm D sb{100}0.3$ mm for gravel; and $ rm D sb{100}<9.5$ mm for crushed rock mixed with sand are suggested. The performance of envelopes meeting these criteria were successful. / The laboratory tests show that the use of a fabric with river sand as an envelope has a very good potential for successful field operation. There was no laboratory evidence to reject the functioning of this concept.

Thesis (Ph.D.)--Syracuse University, 2008. / "Publication number: AAT 3323068."