Download or read book Variability of Saturated Hydraulic Conductivity Measurements Made Using a Flexible Wall Permeameter written by C. H. Benson and published by . This book was released on 2016 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Standard Test Methods for Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter written by and published by . This book was released on 2004 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Standard Test Methods for Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter written by ASTM Committee D-18 on Soil and Rock and published by . This book was released on 2010 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Saturated Hydraulic Conductivity of Poorly Graded Sands with Non Plastic Silt Using a Flexible Wall Permeameter written by Thanabalasingam Sathees and published by . This book was released on 2006 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flexible Wall Permeameter to Measure the Hydraulic Conductivity of Soils in Horizontal Direction written by G. Sridhar and published by . This book was released on 2013 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Laboratory Evaluation of the Constant Rate of Strain and Constant Head Techniques for Measurement of the Hydraulic Conductivity of Fine Grained Soils written by Amy Lynn Adams and published by . This book was released on 2011 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis evaluates the constant rate of strain and constant head techniques for measurement of the hydraulic conductivity of fine grained soils. A laboratory program compares hydraulic conductivity measurements made using both measurement techniques on a total of 12 specimens. Both resedimented and intact materials covering a wide range of plasticity are investigated. Specific material types include Boston Blue Clay, San Francisco Bay Mud, Maine Clay, Ugnu Clay and Kaolinite. Constant rate of strain (CRS) and constant head tests were conducted in a standard Trautwein CRS device modified to allow control of the base pore pressure for constant head testing. A flexible wall permeameter device was used to perform constant head hydraulic conductivity testing on two specimens; this allowed for comparison with the constant head measurements made in the CRS device. A bottom seating error was found in the CRS device. Bottom seating error occurs during set up when the top of the base porous stone is not flush with the bottom of the rigid specimen ring, causing a gap to form between the specimen and the porous stone. A bottom seating error translates into a strain error, which affects both the measured CRS compression and hydraulic conductivity results. Bottom seating error can be avoided using a modified set up procedure. Void ratio errors are sometimes noted between the void ratio measured in the CRS device and that measured upon removal from the CRS device. These errors are likely resultant from specimen swelling following load removal. Based on comparison to the results of an interlaboratory study into the reproducibility of the saturated hydraulic conductivity measured in a flexible wall permeameter, the CRS and constant head techniques were found to measure the same hydraulic conductivity. This conclusion is independent of specimen origin, i.e. resedimented or intact. The CRS and constant head techniques measure the same average hydraulic conductivity even when non uniformities are present, provided the non uniformities are continuous and oriented perpendicular to the axial loading direction.
Download or read book Laboratory Hydraulic Conductivity Testing of GCLs in Flexible Wall Permeameters written by JJ. Bowders and published by . This book was released on 1997 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the important properties of geosynthetic clay liners (GCLs) is hydraulic conductivity. In the laboratory, hydraulic conductivity of GCLs is typically measured in flexible-wall permeameters. The most important variables in hydraulic conductivity testing of GCLs are addressed, including (i) trimming the GCL specimen; (ii) determining the thickness of the specimen; (iii) selecting the effective stress; (iv) selecting the hydraulic gradient; and (v) selecting the first wetting liquid and permeant liquid. A round-robin testing program was conducted in which 18 laboratories independently measured the hydraulic conductivity of a GCL that was permeated with water. The test specimens all came from the same GCL sample. The coefficient of variation, accounting for all sources of variability, was 42%. For experienced laboratories, this value reduced to 35%, which was identical to the variation in quality control tests performed over a 7-month period by the manufacturer on a variety of GCL samples. The round-robin test results are encouraging; there was less variability than might be expected, considering the difficulty in accurately measuring the hydraulic conductivity of relatively impermeable materials such as GCLs.
Download or read book Use of the Velocity head Permeameter to Determine the Saturated Hydraulic Conductivity and for Septic System Site Evaluation written by Kevin Jay Rose and published by . This book was released on 1988 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Standard Test Method for Measurement Og Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter1 written by ASTM International and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Permeability Testing with Flexible Wall Permeameters written by DE. Daniel and published by . This book was released on 1984 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Standard Guideline for Fitting Saturated Hydraulic Conductivity Using Probability Density Functions ASCE EWRI 50 08 written by American Society of Civil Engineers and published by Amer Society of Civil Engineers. This book was released on 2008 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: ASCE/EWRI Standard 50-08 provides current guidelines for fitting saturated hydraulic conductivity using probability density functions. Standard ASCE/EWRI 51-08 addresses the calculation of effective saturated hydraulic conductivity (Ke or Kew) in local-scale groundwater flow, whether or not it is isotropic. Both Standards are bound in the same volume. These are the first in an anticipated series of standards that will address the knowledge of probabilistic characterization and behavior of saturated groundwater conductivity. Saturated hydraulic conductivity is critical in effectively and accurately measuring groundwater flow and transport of contaminants. All saturated hydraulic conductivity measurements are subject to variability even in the most geologically homogeneous aquifers caused by local fluctuations in an aquifer s textural characteristics. Averages of these fluctuations constitute a set of values that can be subsumed into a more general probabilistic description of the sample by means of a probability density function. Applying probabilistic procedures to the saturated hydraulic conductivity allows one to obtain the effective hydraulic conductivity, which can be used to estimate the average specific discharge, the average linear velocity, and other key variables in groundwater flow. The formulas in this publication must be written in the same units International Standard or U.S. These Standards will be useful to environmental engineers, water resources engineers, and anyone who uses hydraulics in engineering.
Download or read book Fixed Wall Versus Flexible Wall Permeameters written by DC. Anderson and published by . This book was released on 1985 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Variability in the Hydraulic Conductivity of a Test Pad Liner System Using Different Testing Techniques written by Matthew Jonathan Nanak and published by . This book was released on 2013 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: Historic methods (the time lag approach, the velocity approach, and the Z-t approach), utilized to reduce two stage borehole test data, were evaluated. Two of the historic methods provided viable results and were used for this research project. Additionally, these two methods are recommended for reducing two stage borehole test data in the future. Flexible wall permeameter and soil index laboratory testing were conducted on the soil used to construct three environmentally controlled compacted clay liners (test pads) to develop a zone of acceptance (placement window). Using the results from the laboratory testing, two acceptance criterions were evaluated, while one criterion was used for construction purposes and is recommended. Two stage borehole testing was conducted in Test Pads 1 and 2, while sealed double ring infiltrometer testing was conducted in Test Pad 3. After in-situ hydraulic conductivity testing was completed for Test Pads 1 and 2, Shelby tube and hand carved samples were obtained and laboratory testing was performed on the samples. Time domain reflectometry probes and tensiometers were used to monitor the movement of the wetting front during testing conducted in Test Pad 3. Hydraulic conductivity results obtained from each testing method were compared. The laboratory obtained hydraulic conductivity values from testing conducted on Shelby tube samples were compared to laboratory hydraulic conductivity values obtained from testing conducted on hand carved samples. The laboratory hydraulic conductivity values obtained from testing conducted on Shelby tube and hand carved samples were compared to field hydraulic conductivity values obtained from two stage borehole hydraulic conductivity testing. The field hydraulic conductivity values obtained from two stage borehole hydraulic conductivity testing were compared to field hydraulic conductivity values obtained from sealed double ring infiltrometer hydraulic conductivity testing. Collection of soil specimens using Shelby tubes causes the soil to compress and thereby changes the soil parameters (unit weight and hydraulic conductivity). Results of this research project indicate that comparable hydraulic conductivities within half an order of magnitude can be obtained from two stage borehole and sealed double ring infiltrometer field testing and laboratory testing conducted on hand carved and Shelby tube flexible wall samples.
Download or read book Techniques to Determine Spatial Variations in Hydraulic Conductivity of Sand and Gravel written by Kathryn M. Hess and published by . This book was released on 1991 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spatial Variability of Saturated Hydraulic Conductivity Under No tillage System written by B.P. Mohanty and published by . This book was released on 1989 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measuring Saturated Hydraulic Conductivity of Soils written by American Society of Agricultural Engineers. Drainage Research Committee and published by . This book was released on 1962 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spatial Variability of Surface and Subsurface Saturated Hydraulic Conductivity in a Semi Arid Region Results from a Field Campaign written by Rike Becker and published by . This book was released on 2016 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: The accurate estimation of saturated hydraulic conductivity (Ks) is of high relevance to correctly reproduce water movement in hydrological simulations. Yet, estimation of Ks is challenging particularly in semi-arid regions with particular soil surface characteristics like crusting and sealing. This study presents results of a field campaign in the semi-arid Walnut Gulch Experimental Watershed, Arizona (US), where surface and subsurface Ks measurements were undertaken across the watershed. Results reveal that the following commonly-used assumptions used in estimation of Ks are not plausible in such regions: (i) Ks decreases with increasing soil depth, (ii) soils with coarse-grained texture (sandy loam) have higher surface Ks values compared to relatively fine-grained texture (fine sandy loam), and (iii) pedo-transfer functions are not reliable methods of estimating Ks. Our results also reveal that remote sensing data can provide useful information for estimation of surface and subsurface Ks values.
