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Drilling-induced isothermal remanent magnetization. Short note
208A is extended to allow computation of water saturation from laboratory measured membrane potential, that potential being a major component of borehole SP. Surface and bulk conductivities are different and, in conjunction with other geometrical parameters (bulk and surface formation factor, pore scale length for bulk and surface transport), give rise to the observed curvature in the conductivity-electrolyte conductivity plot. Dominant current paths shift from surface to pores as electrolyte conductivity increases and effects of the different tortuosities are seen. 904O88 Drilling-induced isothermal remanent magnetization. Short note Pinto, M J; McWilliams, M Geophysics V55. NI, Jan 1990. P I I l - I I 5
Inexpensive paleomagnetic methods are often used to orientate drill cores,but field and laboratory investigations indicate that isothermal remanent magnetization caused by the coring process may overprint and sometimes overpower natural magnetization. A model to describe this phenomenon is derived. Its implications for analysis of paleomagnetic core magnetisation are discussed. 904089 Methylene blue test and the influence of montmorillonite on the behaviour of materials (In French) Frouin, L; Millon-Devigne, P; Tran Ngoc Lan Int Assoc Engng Geol Bull N40. Oct 1989, P91-96
Behaviour of clay-containing geological materials in wet conditions depends on amount and type of clay mineral. For some materials such as cement stabilised soils or concrete, only the external surface is important, but for other materials internal and external surfaces are relevant. Two applications of the methylene blue test are described which allow amount and swelling nature of the clay and ratio of external to internal surface area to be evaluated. Applications are discussed. 904090 Occurrence of small changes in electrical conduction of olivine arising from high-temperature creep Hirsch, L M J Geophys Res V94. NBI2. Dec 1989. P17861-17870
Electrical conductivity of olivine was measured during creep at temperature 1325-1725 deg K arid uniaxial stress 60-180MPa. Small but definite increases in conductivty, weakly correlated with stress and strain, were seen, which remained even after annealing at creep temperature. Results suggest that dislocations do not act directly as channels for enhanced conduction, but may influence conductivity by interaction with other defects. Creep deformation is not considered a mechanism for production of high conductivity layers in the earth crust. 904091 Factors influencing thermal resistivity of sands Brandon, T L: Mitchell, J K J Geotech Engng Div ASCE VII5, NI2. Dec 1989. P16831698
The thermal needle test for measuring the thermal properties of soils has been refined, with attention paid to obtaining consistent soil density across the specimen, good soil-needle contact. sample drying similar to that in field situations, and monitoring and controlling boundary effects. Influences of sand composition, dry density, water content, temperature, and time on thermal resistivity have been investigated. Results are important to study of thermal-geotechnical problems, and may also be useful in interpretation of other geotechnical characteristics of sands.
904092 Mathematical modelling to determine field parameters of diffusing methane gas and carbon dioxide in coal particles Basu, A; Izgi, H; Lama, R D Min Sci Technol VIO. N1, Jan 1990, P23.27
Mathematical modelling of gas diffusion through particulate coal is presented. Laboratory data of gas flow rate against time from a bomb apparatus are matched with theoretical graphs from the diffusion equation to obtain best estimates of concentration of diffusing gas (C) and diffusion coefficient (D). It is necessary to minimise the time between mining, crushing. and sieving of the coal and testing, in order to obtain quality data for calibration of the equations.
904093 Laboratory modelling of sudden coal-methane outbursts with a Hopkinson bar Toth, J; Szabo-Lakatos, J; Pindel, Z Min Sci Technol VIO. N1, Jan 1990, P29-36
A modified Hopkinson pressure bar and gas chromatography were used to model gas outburst and determine the quantity and quality of hydrocarbon gases desorbed from coal by shock waves. Results indicate that desorption occurs instantly after impact, and amount of gas desorbed is 2-3 orders of magnitude greater than before impact. Linear relation exists between amount of gas desorbed and kinetic energy of the striker bar, but the amount is independent of the nature of the mechanical effects. An exponential relation exist between amount of gas desorbed and desorption rate before impact. A semi-quantitative model of the equilibrium developed in the methane-coal system is presented.
904094 Improved field probes for soil water content and electrical conductivity measurement using time domain reflectometry Zegelin, S J; White, I; Jenkins, D R Water Resour Res V25, Nil, Not" 1989, P2367-2376
Volumetric water content and soil conductivity are measured in the laboratory using the transmission line cell, but this instrument is unsuitable for most field soils. The parallel wire or two wire transmission line probes used in situ suffer from unwanted noise and information loss due to impedance mismatch between probe and connecting cable. 3- and 4-wire probes have been designed to overcome these problems. Theoretical considerations and field evaluations are presented.
904095 FE coupled process analysis of buffer mass test in Stripa project Ohnishi, Y; Kobayashi, A Proc 2nd International Symposium on Field Measurements in Geomechanics, Kobe, 6-9 April 1987 V2. P1019-1026. Publ Rotterdam: A A Balkema. 1988
A finite element code for coupled thermo-hydro-mechanical analysis has been developed to examine the behaviour of highly compacted clay (HCC) when used as a buffer material in a heated borehole. Analyses are presented which consider: (I) change of thermal conductivity in HCC during seepage and swelling: (2) change of permeability during seepage and swelling; (3) effects of thermal expansion on thermal conductivity and swelling capacity: and (4) effect of filling material in slot on thermal conductivity, permeability and swelling capacity.
1990 Pergamon Press pie. Reproduction not permitted
Inexpensive paleomagnetic methods are often used to orientate drill cores,but field and laboratory investigations indicate that isothermal remanent magnetization caused by the coring process may overprint and sometimes overpower natural magnetization. A model to describe this phenomenon is derived. Its implications for analysis of paleomagnetic core magnetisation are discussed. 904089 Methylene blue test and the influence of montmorillonite on the behaviour of materials (In French) Frouin, L; Millon-Devigne, P; Tran Ngoc Lan Int Assoc Engng Geol Bull N40. Oct 1989, P91-96
Behaviour of clay-containing geological materials in wet conditions depends on amount and type of clay mineral. For some materials such as cement stabilised soils or concrete, only the external surface is important, but for other materials internal and external surfaces are relevant. Two applications of the methylene blue test are described which allow amount and swelling nature of the clay and ratio of external to internal surface area to be evaluated. Applications are discussed. 904090 Occurrence of small changes in electrical conduction of olivine arising from high-temperature creep Hirsch, L M J Geophys Res V94. NBI2. Dec 1989. P17861-17870
Electrical conductivity of olivine was measured during creep at temperature 1325-1725 deg K arid uniaxial stress 60-180MPa. Small but definite increases in conductivty, weakly correlated with stress and strain, were seen, which remained even after annealing at creep temperature. Results suggest that dislocations do not act directly as channels for enhanced conduction, but may influence conductivity by interaction with other defects. Creep deformation is not considered a mechanism for production of high conductivity layers in the earth crust. 904091 Factors influencing thermal resistivity of sands Brandon, T L: Mitchell, J K J Geotech Engng Div ASCE VII5, NI2. Dec 1989. P16831698
The thermal needle test for measuring the thermal properties of soils has been refined, with attention paid to obtaining consistent soil density across the specimen, good soil-needle contact. sample drying similar to that in field situations, and monitoring and controlling boundary effects. Influences of sand composition, dry density, water content, temperature, and time on thermal resistivity have been investigated. Results are important to study of thermal-geotechnical problems, and may also be useful in interpretation of other geotechnical characteristics of sands.
904092 Mathematical modelling to determine field parameters of diffusing methane gas and carbon dioxide in coal particles Basu, A; Izgi, H; Lama, R D Min Sci Technol VIO. N1, Jan 1990, P23.27
Mathematical modelling of gas diffusion through particulate coal is presented. Laboratory data of gas flow rate against time from a bomb apparatus are matched with theoretical graphs from the diffusion equation to obtain best estimates of concentration of diffusing gas (C) and diffusion coefficient (D). It is necessary to minimise the time between mining, crushing. and sieving of the coal and testing, in order to obtain quality data for calibration of the equations.
904093 Laboratory modelling of sudden coal-methane outbursts with a Hopkinson bar Toth, J; Szabo-Lakatos, J; Pindel, Z Min Sci Technol VIO. N1, Jan 1990, P29-36
A modified Hopkinson pressure bar and gas chromatography were used to model gas outburst and determine the quantity and quality of hydrocarbon gases desorbed from coal by shock waves. Results indicate that desorption occurs instantly after impact, and amount of gas desorbed is 2-3 orders of magnitude greater than before impact. Linear relation exists between amount of gas desorbed and kinetic energy of the striker bar, but the amount is independent of the nature of the mechanical effects. An exponential relation exist between amount of gas desorbed and desorption rate before impact. A semi-quantitative model of the equilibrium developed in the methane-coal system is presented.
904094 Improved field probes for soil water content and electrical conductivity measurement using time domain reflectometry Zegelin, S J; White, I; Jenkins, D R Water Resour Res V25, Nil, Not" 1989, P2367-2376
Volumetric water content and soil conductivity are measured in the laboratory using the transmission line cell, but this instrument is unsuitable for most field soils. The parallel wire or two wire transmission line probes used in situ suffer from unwanted noise and information loss due to impedance mismatch between probe and connecting cable. 3- and 4-wire probes have been designed to overcome these problems. Theoretical considerations and field evaluations are presented.
904095 FE coupled process analysis of buffer mass test in Stripa project Ohnishi, Y; Kobayashi, A Proc 2nd International Symposium on Field Measurements in Geomechanics, Kobe, 6-9 April 1987 V2. P1019-1026. Publ Rotterdam: A A Balkema. 1988
A finite element code for coupled thermo-hydro-mechanical analysis has been developed to examine the behaviour of highly compacted clay (HCC) when used as a buffer material in a heated borehole. Analyses are presented which consider: (I) change of thermal conductivity in HCC during seepage and swelling: (2) change of permeability during seepage and swelling; (3) effects of thermal expansion on thermal conductivity and swelling capacity: and (4) effect of filling material in slot on thermal conductivity, permeability and swelling capacity.
1990 Pergamon Press pie. Reproduction not permitted