Flexible Wall Permeameter To Measure The Hydraulic Conductivity Of Soils In Horizontal Direction
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| Author | : G. Sridhar |
| Publisher | : |
| Total Pages | : 6 |
| Release | : 2013 |
| Genre | : Compressibility |
| ISBN | : |
The flexible wall permeability apparatus was modified for the direct measurement of the hydraulic conductivity of soils in the horizontal direction. Constant head permeability tests were carried out using the radial flow flexible wall permeameter on soil samples with central sand drain to allow the water to flow radially from the central sand drain towards a peripheral drain. Tests were also conducted using the conventional flexible wall permeameter on samples that were trimmed horizontally, so as to measure the hydraulic conductivity in the horizontal directions for comparison. The test results obtained from the proposed setup agrees well with those obtained from the samples that were trimmed horizontally, proving the validity of the results obtained from the proposed apparatus.
| Author | : DE. Daniel |
| Publisher | : |
| Total Pages | : 10 |
| Release | : 1984 |
| Genre | : Compatability |
| ISBN | : |
The equipment and testing procedures used at The University of Texas at Austin for measuring the hydraulic conductivity of fine-grained soil with flexible-wall permeameters are described. The permeability cell is similar to a triaxial cell; it has interchangeable base pedestals to accomodate specimens of various diameters, is equipped with double drainage lines to the top and bottom of the test specimen, and can accomodate a differentially acting pressure transducer to measure head loss across the soil specimen. An air-over-liquid interface is maintained in devices called "accumulators." Stainless steel accumulators designed with transparent sight tubes offer excellent resistance to corrosion, are convenient to use, and can be used with a wide range in flow rates. The permeability tests are normally performed using back pressure. Care is taken to be certain that flow is steady state and that the soil is permeated long enough for the influent liquid to pass through the soil and to appear in the effluent liquid in full concentration. When clays are permeated with dilute chemicals that are adsorbed by the soil, testing times on the order of months or years may be required to achieve full breakthrough of the permeant liquid. Use of large hydraulic gradient and excessive effective confining pressure are sometimes difficult to avoid but are two of the most important sources of potential error.
| Author | : C. H. Benson |
| Publisher | : |
| Total Pages | : 16 |
| Release | : 2016 |
| Genre | : Flexible-wall permeameter |
| ISBN | : |
A study was conducted following the procedures in ASTM E691-14 (Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method) to develop a precision statement for hydraulic conductivity measurement of fine-grained soils using Method C (falling head, rising tailwater elevation) of ASTM D5084-10 (Standard Test Methods for Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter). Twelve laboratories conducted tests on three replicate specimens of three fine-grained soils (9 specimens total per laboratory) from the ASTM Reference Soils Program: Soil ML (silt), Soil CL (low plasticity clay), and Soil CH (high plasticity clay). The data indicated that the measurement variability for hydraulic conductivity is modest but not negligible, and probably contributes to the spatial variability reported in past studies of hydraulic conductivity. No systematic relationships were observed between variability in hydraulic conductivity and testing time (consolidation, permeation), backpressure, B-coefficient achieved at end of consolidation, compliance with the termination criteria, or specimen compaction conditions. Many laboratories did not comply with the test standard or the supplemental instructions, which may indicate that greater oversight of geotechnical laboratories is needed via accreditation and auditing programs. Analysis of the data indicate that hydraulic conductivity can be measured using Method C of ASTM D5084 within a factor of 2 for the 10-6 cm/s range, a factor of 1.5 for the 10-8 cm/s range, and a factor of 4 for the 10-9 cm/s range.
| Author | : |
| Publisher | : |
| Total Pages | : 23 |
| Release | : 2004 |
| Genre | : Porous materials |
| ISBN | : |
| Author | : DC. Anderson |
| Publisher | : |
| Total Pages | : 20 |
| Release | : 1985 |
| Genre | : Clay |
| ISBN | : |
Permeameters are of two general types: fixed-wall and flexible-wall cells. A controversy has developed over which type of cell is best suited for measuring the hydraulic conductivity of relatively impermeable, fine-grained soils. The various types of permeameters are discussed and their relative advantages and disadvantages are listed. Differences in applied stress, boundary leakages, and degree of saturation are the major differences between cells. It is concluded that no one type of cell is best suited to all applications. Data show that the type of permeameter used has little effect for laboratory-compacted clay permeated with water but can have a major effect for clays permeated with concentrated organic chemicals. Fixed-wall cells are perhaps best suited to testing laboratory-compacted clays that will be subjected to little or no effective overburden pressure in the field. Flexible-wall cells are better suited to testing undisturbed samples of soil (to minimize boundary leakages) and testing soils that will be subjected to significant effective stress.
| Author | : ASTM Committee D-18 on Soil and Rock |
| Publisher | : |
| Total Pages | : 46 |
| Release | : 2010 |
| Genre | : Porous materials |
| ISBN | : |
| Author | : Daniel B. Stephens |
| Publisher | : CRC Press |
| Total Pages | : 347 |
| Release | : 2018-02-06 |
| Genre | : Science |
| ISBN | : 1351405802 |
Vadose Zone Hydrology describes the elements of the physical processes most often encountered by hydrogeologists and ground-water engineers in their vadose zone projects. It illustrates the application of soil physics to practical problems relevant to the characterization and monitoring of the vadose zone. It includes an introduction to physical processes, including basic flow theory, and provides examples of important field-scale processes that must be recognizable by hydrogeologists. Considerable attention is given to the concepts of recharge, including how it is most accurately evaluated in the vadose zone. Field and laboratory methods for characterizing hydraulic properties in the vadose zone are also covered, and case studies illustrating these methods are provided. New and emerging technologies for monitoring the vadose zone, particularly for the purpose of detecting contaminants, are highlighted. In the last section of the book, additional case studies are presented, demonstrating applications related to seepage detection, landfill monitoring, and soil gas investigations. This book is written from the perspective of hydrogeologists and is designed to be directly applicable and to maintain continuity and consistency between chapters. It will be an invaluable primer for environmental or geotechnical consultants, regulators, or students who have no prior formal academic training in unsaturated flow concepts. Because the text contains some of the latest advances in this field, it will be an excellent reference for geologists and engineers currently working on problems of vadose zone hydrology.
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| Total Pages | : 0 |
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| Total Pages | : 0 |
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| Author | : M. P. H. Moncada |
| Publisher | : |
| Total Pages | : 12 |
| Release | : 2011 |
| Genre | : Constant flow method |
| ISBN | : |
This paper describes the development of a suction controlled flexible wall permeameter for the direct determination of the water permeability function in unsaturated soils. The new permeameter works with applied constant head or constant rate of flow, i.e., the common steady-state techniques. Total volume change of soil specimens during the test are monitored using a high resolution electronic scale. Numerical simulations were performed to evaluate the influence of factors such as flow velocity and matric suction distribution within the specimen and effects of sample height on such factors. Analyses of tests conducted on two tropical soil samples are used to evaluate conventional proposals for the determination of the water permeability function. It is shown that such proposals do not apply in the case of the materials tested and solutions to that are put forwards.
