- Email: [email protected]
Laboratory and field studies of the application of electromagnetic prospecting for groundwater on Marajo Island, Brazil
245A •hydraulic and energy budgets of a soil is presented. Using this, it is possible to obtain hydrological information via surface temperature infrared remote sensing data.
Structural and geotechnical mapping 895131 Preliminary studies on the geotechnical characteristics of the Niger delta subsoils Akpokodje, E G Engng Geol V26, N3. March 1989. P247-259 The subsoil of the Niger delta was studied using data from boreholes and previous investigations. The delta may be divided into 3 zones based on stratigraphy and geotechnical characteristics: (I) clayey sandy subsoil of the flat, dry plains; (2) 2-layer clay-sand of the swamps: and (3) 3-layer sand-claysand of the coastal beaches and ridges. In zones 2 and 3, frequent changes occur due to lenticular sedimentation, and there is a progressive seaward deterioration of foundation conditions due to greater quantities of clays and peats. 895132 Contribution of the measurement of electrical anisotropy to the study of fractured aquifers in crystalline formations in Benin (In French) Darboux-Afouda, R: Louis, P Geophys Prospect V37. NI, Jan 1989, P91-105 To survey crystalline formations with a thin weathered zone and locate the fractured zones in the basement, a combination of electrical profiling. Schlumberger and square arrays was used. Both resistivity and anisotropy were measured. The most productive hydrological areas showed strong anisotropy and low resistivity. Results of theoretical models and field data are presented. 895133 Fracture mapping on outcrops in crystalline bedrock: a case study within the subcambrian peneplain, southern Sweden Ericsson, L O; Ronge, B S H Key Questions in Rock Mechanics: Proc 29th US Symposium, Minneapolis, 13-15 June 1988 P731-732. Publ Rotterdam: A A Balkema. 1988 Over 10.OO0 fracture observations were made from over 140 outcrops and road cuts within an area of about 400 sq km, in order to produce results for subsequent geohydrological and rock mechanical model studies to select an underground laboratory site. it is indicated that rock stress history and fracture set data are correlated with each other. Further detailed hydrological investigation is being continued. 895134 Geotechnical engineering mapping of the Taipei city Huang. C T; Lin, Y K: Kao, T C; Moh, Z C Proc Ninth Southeast Asian Geotechuical Conference, Bangkok, 7-11 December 1987 VI. P3.109-3.120. Publ Bangkok: Southeast Asian Geotechnical Society, 1987 Existing data from borehole logs and laboratory tests were used to divide the Taipei basin into 3 different zones based on depositional characteristics, stratigraphy and engineering properties. The regions were then further divided into 7 zones by analysis of composition, thickness of various strata and engineering properties of the soils. A series of geotechnical engineering maps was produced including a geological map, fence diagrams, isopachous maps of various sublayers, and a geotechnical zoning map.
Geophysical techniques 895135 Further development of a high-frequency seismic source for use in boreholes Baria, R; Jackson, P D; McCann, D M Geophys Prospect 1/37. N1, Jan 1989, P31-52 Development and field trials of an improved borehole sparker probe are described. Laboratory assessment of parameters which control the output power and overall performance are illustrated. Because of its repetitive nature, high frequency content, and reliability, the source is ideal for tomographic imaging. Very high resolution seismic surveys are also possible under favourable conditions.
895136 Recent developments in underground gravity surveys Casten, U; Gram, C Geophys Prospect V37, NI, Jan 1989, P73-90 Gravity observations are used for density determination. exploration and safety controls. They are made from the surface and in underground structures. In the latter case, correction must be made for cavity effects, in general the effects of the gallery in which the observations are made. A new cavity correction method is described, which allows in situ density determination, and horizontal instead of vertical density profiling. An example of cavity locating utilising the methods is presented.
895137 Radar sounding in potash mines, Saskatchewan, Canada Annan, A P; Davis, J L; GendzwiU, D Geophysics 1/53, N12, Dec 1988, P!556-1564 Radar sounding experiments were carried out to assess the effectiveness of the technique in salt environments. Stratigraphy of beds above, below and beside mine tunnels was examined using an impulse radar system. High frequency antennas detected thin clay beds and stress relief cracks to depths of several metres, whilst lower frequency antennas were more useful for deeper soundings up to 20m depth. Deeper structures were often masked by high reflectivity stress relief cracks. Bulk dielectric constant of the deposit was 5-6. Depth of penetration was greater in areas of low clay content.
895138 Laboratory and field studies of the application of electromagnetic prospecting for groundwater on Marajo Island, Brazil Verma, 0 M; Bischoff, J H Geophysics 1/54. NI, Jan 1989. P23-30 Two types of fresh water aquifers were discovered by conventional electromagnetic methods, one at about 100m depth, the other in shallow buried-stream channels filled with sand and gravel and embedded in clay and sand beds. The latter is conveniently exploited by farmers. To verify the applicability of EM survey techniques for groundwater exploration, analogue model studies of the shallow aquifer were undertaken. Excellent EM model responses were obtained for six electrode configurations. Field and laboratory results were in good qualitative agreement.
C~ 1989 Pergamon Press pic. Reproduction not permitted RNIMS 26 ~ H
Structural and geotechnical mapping 895131 Preliminary studies on the geotechnical characteristics of the Niger delta subsoils Akpokodje, E G Engng Geol V26, N3. March 1989. P247-259 The subsoil of the Niger delta was studied using data from boreholes and previous investigations. The delta may be divided into 3 zones based on stratigraphy and geotechnical characteristics: (I) clayey sandy subsoil of the flat, dry plains; (2) 2-layer clay-sand of the swamps: and (3) 3-layer sand-claysand of the coastal beaches and ridges. In zones 2 and 3, frequent changes occur due to lenticular sedimentation, and there is a progressive seaward deterioration of foundation conditions due to greater quantities of clays and peats. 895132 Contribution of the measurement of electrical anisotropy to the study of fractured aquifers in crystalline formations in Benin (In French) Darboux-Afouda, R: Louis, P Geophys Prospect V37. NI, Jan 1989, P91-105 To survey crystalline formations with a thin weathered zone and locate the fractured zones in the basement, a combination of electrical profiling. Schlumberger and square arrays was used. Both resistivity and anisotropy were measured. The most productive hydrological areas showed strong anisotropy and low resistivity. Results of theoretical models and field data are presented. 895133 Fracture mapping on outcrops in crystalline bedrock: a case study within the subcambrian peneplain, southern Sweden Ericsson, L O; Ronge, B S H Key Questions in Rock Mechanics: Proc 29th US Symposium, Minneapolis, 13-15 June 1988 P731-732. Publ Rotterdam: A A Balkema. 1988 Over 10.OO0 fracture observations were made from over 140 outcrops and road cuts within an area of about 400 sq km, in order to produce results for subsequent geohydrological and rock mechanical model studies to select an underground laboratory site. it is indicated that rock stress history and fracture set data are correlated with each other. Further detailed hydrological investigation is being continued. 895134 Geotechnical engineering mapping of the Taipei city Huang. C T; Lin, Y K: Kao, T C; Moh, Z C Proc Ninth Southeast Asian Geotechuical Conference, Bangkok, 7-11 December 1987 VI. P3.109-3.120. Publ Bangkok: Southeast Asian Geotechnical Society, 1987 Existing data from borehole logs and laboratory tests were used to divide the Taipei basin into 3 different zones based on depositional characteristics, stratigraphy and engineering properties. The regions were then further divided into 7 zones by analysis of composition, thickness of various strata and engineering properties of the soils. A series of geotechnical engineering maps was produced including a geological map, fence diagrams, isopachous maps of various sublayers, and a geotechnical zoning map.
Geophysical techniques 895135 Further development of a high-frequency seismic source for use in boreholes Baria, R; Jackson, P D; McCann, D M Geophys Prospect 1/37. N1, Jan 1989, P31-52 Development and field trials of an improved borehole sparker probe are described. Laboratory assessment of parameters which control the output power and overall performance are illustrated. Because of its repetitive nature, high frequency content, and reliability, the source is ideal for tomographic imaging. Very high resolution seismic surveys are also possible under favourable conditions.
895136 Recent developments in underground gravity surveys Casten, U; Gram, C Geophys Prospect V37, NI, Jan 1989, P73-90 Gravity observations are used for density determination. exploration and safety controls. They are made from the surface and in underground structures. In the latter case, correction must be made for cavity effects, in general the effects of the gallery in which the observations are made. A new cavity correction method is described, which allows in situ density determination, and horizontal instead of vertical density profiling. An example of cavity locating utilising the methods is presented.
895137 Radar sounding in potash mines, Saskatchewan, Canada Annan, A P; Davis, J L; GendzwiU, D Geophysics 1/53, N12, Dec 1988, P!556-1564 Radar sounding experiments were carried out to assess the effectiveness of the technique in salt environments. Stratigraphy of beds above, below and beside mine tunnels was examined using an impulse radar system. High frequency antennas detected thin clay beds and stress relief cracks to depths of several metres, whilst lower frequency antennas were more useful for deeper soundings up to 20m depth. Deeper structures were often masked by high reflectivity stress relief cracks. Bulk dielectric constant of the deposit was 5-6. Depth of penetration was greater in areas of low clay content.
895138 Laboratory and field studies of the application of electromagnetic prospecting for groundwater on Marajo Island, Brazil Verma, 0 M; Bischoff, J H Geophysics 1/54. NI, Jan 1989. P23-30 Two types of fresh water aquifers were discovered by conventional electromagnetic methods, one at about 100m depth, the other in shallow buried-stream channels filled with sand and gravel and embedded in clay and sand beds. The latter is conveniently exploited by farmers. To verify the applicability of EM survey techniques for groundwater exploration, analogue model studies of the shallow aquifer were undertaken. Excellent EM model responses were obtained for six electrode configurations. Field and laboratory results were in good qualitative agreement.
C~ 1989 Pergamon Press pic. Reproduction not permitted RNIMS 26 ~ H