Permeability Of Clay Research Articles

A Simple Automatic Falling Head Permeameter

The usual method of measuring the permeability of a homogeneous soil in the laboratory is a constant head or a falling head test. Of the two methods, the falling head test is more suitable for measuring the permeability of homogeneous clay as very small flow quantities are involved. The proposed method is to keep the conventional falling head test unchanged except to measure the falling head automatically through a very accurate differential pressure transducer. The low pressure end of the transducer is opened to the atmosphere to correct for changes in the atmospheric pressure over the 24 hour duration of a typical permeability test. By means of several repeated falling head permeability tests at different initial heads for the same effective stresses, it is demonstrated that reasonably reliable and repeatable measurements of permeabilities of clay can be made, provided that the applied head difference as a proprtion of the current vertical stress is swelling is induced by the seepage head.

Loblolly Pine Plantation Development is Influenced by Site Preparation and Soils in the West Gulf Coastal Plain

Abstract Productivity of upland loblolly pine (Pinus taeda L.) plantations was studied under seven site preparation treatments and five soil classes, with and without fertilizer, in the West Gulf Coastal Plain. Generally, the chop-burn-harrow and shear-windrow-harrow treatments resulted in themost basal area (ave. 112 ft²/ac), but the chop-burn-harrow treatment produced the most fiber (2,109 ft³/ac) after 12 growing seasons. Harrowing as an additional treatment after chopping-and-burning increased productivity by 394 ft³/ac over the chop-burn treatment. The leastproductive treatments were underplant-inject and shear-windrow. Generally, basal area per acre was comparatively high on the silty, slowly permeable clay, and very slowly permeable clay soils (ave. 105 ft ²/ac). Two of the soils, silty and slowly permeable clay, had comparatively highvolume production (ave. 1,878 ft³/ac). The least productive sites had gravelly subsoils. Generally, phosphorus fertilization did not influence pine productivity. South. J. Appl. For. 13(1):17-21.

Laboratory modelling of fractured clay for hazardous waste studies

The integrity and permeability of a clay mass that acts as a waste confining layer will be controlled by local defects such as desiccation cracks, fissures and fractures. In the Gulf Coast region, growth faults associated with natural geological processes and fluid withdrawal accelerate the production of local defects. Laboratory permeability tests conducted on recompacted samples or small undisturbed samples are unlikely to contain representative pattern of cracks and fissures and significantly under-predict the hydraulic conductivity of clay (natural deposits or liners) by several orders of magnitude. Although large-scale in-situ permeability tests may provide correct permeability information in accessible soils (near-surface), the time period required to conduct tests makes them impractical and hence it is essential to develop laboratory tests procedures to model closely the field conditions. Several methods of simulating cracks in the laboratory clay samples were investigated by using double ring-rigid wall permeameters. By inserting syringe needles of various sizes (gage numbers) and lengths defects were introduced into the compacted clay samples (simulating cracks) and the preliminary results indicate that the permeability of clay could be increased in a controlled manner. Using this technique, several tests are underway to investigate the effect of crack length, size and density on the permeability of Kaolinite clay. Relationship between permeability and crack length have been developed and the concept of effective clay thickness and effective permeability is introduced based on crack length. Numerical simulations based on a finite element model are being used to verify the experimental results.

Permeability of Clays Under Organic Permeants

A magnesium montmorilionite and a kaolinite clay are subjected to organic and inorganic permeants to study the changes in permeability caused by the reaction between clays and permeants. The permea...

不撹乱粘土試料の水平方向透水係数の測定方法

不撹乱粘土試料の水平方向透水係数の測定方法

Direct determination of permeability of clay under embankment : Leroueil, S; Diene, M; Tavenas, F; Kabbaj, M; La Rochelle, P J Geotech Engng Div ASCEV114, N6, June 1988, P645–657

This discussion concerns the integrity of methodology applied to a Lagrangian coordinate system used in describing the consolidation of a clay layer. The discussers question the legitimacy of the paper based on the use of an incorrect equation in evaluating real permeability. Counter-discussers state that the equation is misunderstood by the discussers. The counter-discussers also suggest alternate interpretation of excess pore pressure profiles presented in the original paper. The writers conclude that the proposed method is sound, but with the asumption of one dimensional consolidation and availability of high-quality instrumentation data.

Effects of organic fluids on clay permeability: Parker, F; Benefield, L D; Nelson, M M Proc 41st Industrial Waste Conference, West Lafayette, 13–15 May 1986P283–292. Publ Chelsea, Michigan: Lewis, 1987

Effects of organic fluids on clay permeability: Parker, F; Benefield, L D; Nelson, M M Proc 41st Industrial Waste Conference, West Lafayette, 13–15 May 1986P283–292. Publ Chelsea, Michigan: Lewis, 1987

Discussion of “ Termination Criteria for Clay Permeability Testing ” by J. Jeffrey Peirce and Kelly A. Witter (September, 1986, Vol. 112, No. 9)

Discussion of “ <i>Termination Criteria for Clay Permeability Testing</i> ” by J. Jeffrey Peirce and Kelly A. Witter (September, 1986, Vol. 112, No. 9)

Closure to “ Termination Criteria for Clay Permeability Testing ” by J. Jeffrey Peirce and Kelly A. Witter (September, 1986, Vol. 112, No. 9)

Closure to “ <i>Termination Criteria for Clay Permeability Testing</i> ” by J. Jeffrey Peirce and Kelly A. Witter (September, 1986, Vol. 112, No. 9)

Direct Determination of Permeability of Clay under Embankment

Numerous methods are used to measure the permeability of clays in laboratory and in situ. It is well known that these methods lead to different \Ik\N values, but, until now, no comparison with the “real in situ permeability” has been carried out. In this paper a method based on the observation of pore pressure isochrones and settlement rates under embankments is proposed to determine the “real” in situ \Ik\N value at various depths and at various times and strains. This method is successfully applied to the Berthierville test embankment where different permeability tests have been carried out. The results show that on this site: the “real” in situ permeability is slightly higher than the permeability obtained by direct measurement in laboratory; the coefficient of permeability deduced from c\I\dv\N values strongly underestimates the in situ permeability; and the coefficient of permeability measured with the self-boring permeameter is representative of the “real” in situ permeability while the coefficient measured by means of pushed-in-place piezometers underestimates it.

Effects of selected inorganic leachates on clay permeability. Technical note : Peirce, J J; Sallfors, G; Peel, T A; Witter, K A J Geotech Engng Div ASCEV113, N8, Aug 1987, P915–919

Effects of selected inorganic leachates on clay permeability. Technical note : Peirce, J J; Sallfors, G; Peel, T A; Witter, K A J Geotech Engng Div ASCEV113, N8, Aug 1987, P915–919

Effects of selected inorganic leachates on clay permeability. Technical note : Peirce, J J; Sallfors, G; Peel, T A; Witter, K A J Geotech Engng Div ASCEV113, N8, Aug 1987, P915–919

Effects of selected inorganic leachates on clay permeability. Technical note : Peirce, J J; Sallfors, G; Peel, T A; Witter, K A J Geotech Engng Div ASCEV113, N8, Aug 1987, P915–919

Hydraulic Conductivity of Compacted Clay to Dilute Organic Chemicals

Four organic chemicals over a range of concentrations were permeated through compacted specimens of kaolinite and illite‐chlorite. Permeability tests were performed in both rigid and flexible‐wall permeameters. Soil index tests were modified for use in evaluating the effect an organic waste may have on clay. Results of the investigation showed that dilute organic chemicals (less than 80% by volume in an aqueous solution) have little effect on the hydraulic conductivity (permeability) of compacted clay. The modified index tests showed good correlation to the degree with which an organic liquid affects the hydraulic conductivity of the compacted clay.

Effects of Selected Inorganic Leachates on Clay Permeability

The widespread use of clays as liner materials for hazardous waste disposal facilities has sparked an interest in the effects that inorganic chemicals have on the hydraulic conductivity of clays. Three natural clays are permeated with nickel nitrate and ferric chloride, and their hydraulic conductivities are determined to be in the range of 10û8 cm/s which does not differ from their hydraulic conductivities to water as measured in both fixed- and flexible-wall permeameters. Results of the hydraulic conductivity tests indicated that at the concentrations tested, nickel nitrate (50 mg/L and 300 g/L) and ferric chloride (500 mg/L) do not significantly affect the hydraulic conductivities of the three field clays tested, even upon the passage of as many as 50 pore volumes of permeant into the sample.

Protection of Waterlines Traversing a Hazardous Waste Landfill

Water plant intake lines for the city of Toledo, Ohio, pass through a privately operated hazardous waste disposal site. Safeguards were negotiated with the operators of the disposal site to protect the intake lines from possible contamination. The waterline security agreement described in this article was accomplished outside of regulatory processes since there were no specific federal, state, or local regulations covering such a situation. The agreement with the landfill operators includes design requirements and safeguards that provide for an estimated 60 to 6000 years of advance warning of contamination, based on the range of clay permeability, if an unlikely leak travels toward the easement from the hazardous waste storage cells.

Termination criteria for clay permeability testing : Peirce, J J; Witter, K A J Geotech Enggn Div ASCEV112, N9, Sept 1986, P841–854

Termination criteria for clay permeability testing : Peirce, J J; Witter, K A J Geotech Enggn Div ASCEV112, N9, Sept 1986, P841–854

Shear strength parameters between geomembranes and cohesive soils

This paper focuses on the shear strength of various geomembranes and a number of different cohesive soils. The data base is felt to be necessary since geomembranes used in solid waste disposal are often placed directly on low permeability clay soils. Adapted direct shear tests were performed allowing for a determination of adhesion and friction angle values. It was seen that the adhesion of the soil to the geomembrane is significantly reduced from the cohesion value of the soil itself, unless the geomembrane is very soft or textured. Conversely, the friction angle at the interface between the geomembrane and the soil is relatively high, at least for the normal pressures used in these tests. The information presented is felt to be the type necessary for a number of practical design considerations.

Clay Liner Permeability: Evaluation and Variation

The primary criterion used in evaluating the suitability of hazardous waste landfills for containing hazardous wastes is permeability, and many regulatory agencies have adopted regulations requiring clay-lined hazardous waste landfills to have a coefficient of permeability no greater than a fixed value. However, the measurement of in-situ permeability of compacted clay is time-consuming and difficult. If used to monitor construction, it slows the construction rate. Another equally important problem is that clay-liner permeability is extremely variable. Solutions to both of these problems are presented. Firstly, a relationship is developed between permeability and easily measured dry unit weight and moisture content. This would allow for the immediate monitoring of clay liners during construction. Secondly, an alternative is provided to the conventional approach in which permeability is treated as a single-valued quantity. A probabilistic description of the permeability of clay liners is developed from considerations of the heterogeneity of the soil. This would improve the design of clay liners by establishing confidence levels associated with possible ranges of the permeability.

Verifying estimates of field capacity for some New Zealand soils

Abstract Core samples were taken from 7 soils in North Auckland in late winter-spring, a few days after heavy rain. The weights of the cores at sampling were compared with the weights attained subsequently after saturation and drainage to a series of water tensions in a pressure plate apparatus. For both the free-draining brown loams and the slowly permeable yellow-brown earths and brown granular clays the water contents in the field corresponded to tensions of 0.05–0.25 bar (5–25 kPa). Four free-draining soils from the North Island, on which determinations of this type had been made, either as above or in a previous investigation, were re-sampled. The hydraulic conductivities of the samples were measured. At tensions corresponding to the water contents of the earlier determinations conductivities ranged from 1.1 × 10-9-1.5 × 10-8 m/s. These conductivities would produce drainage rates of 1.1 × 10-9-1.5 × 10-8m/s (0.1–1.3 mm/day) under gravity, representing negligible further drainage.

Permeability of fault gouge under confining pressure and shear stress

The permeability of both clay‐rich and non‐clay gouges, as well as several pure clays, was studied as a function of confining pressures from 5 to 200 MPa and shear strain to 10. Permeability ranged over four orders of magnitude, from around 10−22 to 10−18 m2 (1 darcy = 0.987 × 10−12 m2). The lowest values were characteristic of the montmorillonite‐rich and finer grained non‐clay gouges. Illite, kaolinite, and chlorite had intermediate permeabilities, while the highest values were typical of the serpentine and coarser grained non‐clay gouges. Grain size was an important factor in determining permeability, particularly for the clay‐rich samples. The coarse grained gouges were the most permeable and decreased in permeability after shearing. Conversely, the fine grained gouges had characteristically lower permeabilities that did not vary significantly after various amounts of shearing. The permeabilities of the non‐clay samples were not significantly different than those of the clays. Therefore, comminuted rock flours can be equally as effective in reducing the flow of water as the characteristically low permeability clay gouges. The strengths of the samples were quite variable. The non‐clay gouges were consistently the strongest, with yield points (beginning of nonelastic behavior) around 850 MPa, while montmorillonite had an anomalously low strength in relation to all the other gouges at 250 MPa. Strength of the saturated samples under drained (low pore pressure) conditions did not correlate with high or low permeability. However, the low permeabilities of these gouges could be a factor in the measured low shear stresses along fault regions if excess pore pressures were created as a result of shearing or compaction, and this pressure was unable to dissipate through a thick section of the material.