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Georadar surveys: theoretical principles and applied cases (In Italian)
278A
905186 Liquefaction potential map for Charleston. South Carolina Elton, D J; Hadj-Hamou, T J Geotech Engng Div ASCE VII6. N2, Feb 1990. P244-265 Liquefaction potential of saturated cohesionless deposits was evaluated probabilistically, combining liquefaction susceptibility (critical acceleration required) and liquefaction opportunity (seismic threat). Probability is evaluated by comparing acceleration at a site with that required to cause liquefaction. Results are presented as maps of zones of different risk levels and via normalised liquefaction index of the probability of liquefaction. Examination of over 200 boring logs showed soil variability as a result of filling for reclamation over 300 years. Peninsular Charleston has moderate liquefaction potential.
9O5187 Reconnaisunce-level biogeochemlcal surveys for gold in
Canada Dunn, C E Trans inst Min Metuli (Sect B Appl Earth Sei) V98, SeptDec 1989, PBI53-BI61 Biogeochemical surveys may provide information on the substrate which cannot be obtained from other surficial materials, as root systems extract elements from a spectrum of soil horizons, their groundwater, and even bedrock. Such a survey has been carried out in the La Ronde gold belt of Saskatchewan, with sampling intervals of 2kin. Drilling on biogeochemical anomalies has already encountered gold mineralisation, and other anomalous areas are under investigation. Even very sparse sampling outlines areas of known mineralisation.
905188 Methodology of geological and rock mechanics studies for underground nuclear plants Moro, T Tmmlg Underground Space Tectmol V5, N1/2, 1990, P103110 Seismic stability of nuclear plants can be improved by locating them underground. A geological and geomechanical outline for placing of such structures is presented. Initial stages involve study of neotectonic elements, geological maps, and aerial photographs, plus in situ surface geological studies. Following initial design stages, test adits are excavated, and laboratory testing undertaken. Final detailed design studies include measurements of displacements and convergence during construction.
905190 Nuclear logging developed by the Laburatoires des Ponts et Chaussees: physical principles, implementation and field of application (In French) Baron, J P; Cariou, J; Thorin, R Bull Liaison Labs Ponts Chaussees N164, Not'-Dec 1989, P17-24 The principles of the various types of nuclear logging, natural radioactivity, gamma-gamma, neutron-neutron, and neutron capture, and the requisite equipment and its application are outlined. Applications by the LPC are described, with particular reference to artificial radioactivity logging on karstic rocks, natural soils and embankments, soils difficult to sample, and structures under or over water. The advantages of nuclear methods in these cases are discussed.
905191 Application of electric polarization to contaminant detection in soils Yong, R N; Hoppe, E J Can Geotech J V26, N4, Not" 1989. t'536-550 Time domain reflectometry has been used to assess characteristic signatures of various soils and soil-contaminant mixtures. Differentiation of the signatures is sufficient for their use in assessment of soil status. Electrical polarization methods, similar in principle to induced polarization used in mineral exploration, can be used for contamination detection.
905192 Georadar surveys: theoretical winciples and applied cases (In Italian) Sorlini, A Gallerie N30, 1990, P31-39 The history of ground penetrating radar is briefly described and the theoretical principles outlined. Two case studies using GPR are described. In the first, GPR was used to delineate a karst cavity near the pilot boring for the Furlo tunnel. In the second, it was used to examine cohesive and cohesionless alluvium beneath a factory site. The advantages and disadvantages of GPR as compared to other geophysical methods are discussed, with reference to instances where it is not possible to use methods other than GPR.
905193 Seismic tomographic imaging of a buried concrete target Bishop, I; Styles, P Geophys Prospect 1/38, N2, Feb 1990, P169-188
9O5189 Magnetometer and gradiometer surveys for detection of underground storage tanks
Field evaluation of an algebraic reconstruction technique for seismic tomographic imaging of subsurface velocity anomalies is described. A three dimensional, L-shaped concrete model was buried in a uniform, homogeneous site, an old, levelled, coal spoil tip. Seismic traveltime data through the model were collected. Reconstructions are compared to the model. Accurate data are essential as relatively small errors in traveltime can seriously degrade the reconstruction.
Sehlinger, C M Bull Assoc gngng Geol V27, NI. Feb 1990. P37-50
905194
Geophysical techniques See also: 905166
Environmental pollution concern in the USA has led to interest in methods of locating underground storage facilities. Magnetometer and magnetic gradiometer surveys have been evaluated for this purpose at two sites, one paved, one gravelled, in a deposit of interbedded silt, sand, gravel and clay lenses. Test procedures, data interpretation and presentation are described. Steel storage tanks were readily located. Location of concrete or glass fibre tanks, where the source of the magnetic anomaly is the void itself, will require careful data analysis and interpretation.
Geophysical exploration for gold - a review Doyle, H A Geophysics 1/55, N2, Feb 1990, P134-146 Direct physical response from gold is extremely rare, because of the low grades in deposits, but indirect geophysical indications may occur because of its association with particular host rocks, marker beds, or structures with unusual properties. These various geological features, their specific attributes, and suitable geophysical techniques for their detection are reviewed. 92 refs.
:~) 1990 Pergamon Press pie. Reproduction not permitted
905186 Liquefaction potential map for Charleston. South Carolina Elton, D J; Hadj-Hamou, T J Geotech Engng Div ASCE VII6. N2, Feb 1990. P244-265 Liquefaction potential of saturated cohesionless deposits was evaluated probabilistically, combining liquefaction susceptibility (critical acceleration required) and liquefaction opportunity (seismic threat). Probability is evaluated by comparing acceleration at a site with that required to cause liquefaction. Results are presented as maps of zones of different risk levels and via normalised liquefaction index of the probability of liquefaction. Examination of over 200 boring logs showed soil variability as a result of filling for reclamation over 300 years. Peninsular Charleston has moderate liquefaction potential.
9O5187 Reconnaisunce-level biogeochemlcal surveys for gold in
Canada Dunn, C E Trans inst Min Metuli (Sect B Appl Earth Sei) V98, SeptDec 1989, PBI53-BI61 Biogeochemical surveys may provide information on the substrate which cannot be obtained from other surficial materials, as root systems extract elements from a spectrum of soil horizons, their groundwater, and even bedrock. Such a survey has been carried out in the La Ronde gold belt of Saskatchewan, with sampling intervals of 2kin. Drilling on biogeochemical anomalies has already encountered gold mineralisation, and other anomalous areas are under investigation. Even very sparse sampling outlines areas of known mineralisation.
905188 Methodology of geological and rock mechanics studies for underground nuclear plants Moro, T Tmmlg Underground Space Tectmol V5, N1/2, 1990, P103110 Seismic stability of nuclear plants can be improved by locating them underground. A geological and geomechanical outline for placing of such structures is presented. Initial stages involve study of neotectonic elements, geological maps, and aerial photographs, plus in situ surface geological studies. Following initial design stages, test adits are excavated, and laboratory testing undertaken. Final detailed design studies include measurements of displacements and convergence during construction.
905190 Nuclear logging developed by the Laburatoires des Ponts et Chaussees: physical principles, implementation and field of application (In French) Baron, J P; Cariou, J; Thorin, R Bull Liaison Labs Ponts Chaussees N164, Not'-Dec 1989, P17-24 The principles of the various types of nuclear logging, natural radioactivity, gamma-gamma, neutron-neutron, and neutron capture, and the requisite equipment and its application are outlined. Applications by the LPC are described, with particular reference to artificial radioactivity logging on karstic rocks, natural soils and embankments, soils difficult to sample, and structures under or over water. The advantages of nuclear methods in these cases are discussed.
905191 Application of electric polarization to contaminant detection in soils Yong, R N; Hoppe, E J Can Geotech J V26, N4, Not" 1989. t'536-550 Time domain reflectometry has been used to assess characteristic signatures of various soils and soil-contaminant mixtures. Differentiation of the signatures is sufficient for their use in assessment of soil status. Electrical polarization methods, similar in principle to induced polarization used in mineral exploration, can be used for contamination detection.
905192 Georadar surveys: theoretical winciples and applied cases (In Italian) Sorlini, A Gallerie N30, 1990, P31-39 The history of ground penetrating radar is briefly described and the theoretical principles outlined. Two case studies using GPR are described. In the first, GPR was used to delineate a karst cavity near the pilot boring for the Furlo tunnel. In the second, it was used to examine cohesive and cohesionless alluvium beneath a factory site. The advantages and disadvantages of GPR as compared to other geophysical methods are discussed, with reference to instances where it is not possible to use methods other than GPR.
905193 Seismic tomographic imaging of a buried concrete target Bishop, I; Styles, P Geophys Prospect 1/38, N2, Feb 1990, P169-188
9O5189 Magnetometer and gradiometer surveys for detection of underground storage tanks
Field evaluation of an algebraic reconstruction technique for seismic tomographic imaging of subsurface velocity anomalies is described. A three dimensional, L-shaped concrete model was buried in a uniform, homogeneous site, an old, levelled, coal spoil tip. Seismic traveltime data through the model were collected. Reconstructions are compared to the model. Accurate data are essential as relatively small errors in traveltime can seriously degrade the reconstruction.
Sehlinger, C M Bull Assoc gngng Geol V27, NI. Feb 1990. P37-50
905194
Geophysical techniques See also: 905166
Environmental pollution concern in the USA has led to interest in methods of locating underground storage facilities. Magnetometer and magnetic gradiometer surveys have been evaluated for this purpose at two sites, one paved, one gravelled, in a deposit of interbedded silt, sand, gravel and clay lenses. Test procedures, data interpretation and presentation are described. Steel storage tanks were readily located. Location of concrete or glass fibre tanks, where the source of the magnetic anomaly is the void itself, will require careful data analysis and interpretation.
Geophysical exploration for gold - a review Doyle, H A Geophysics 1/55, N2, Feb 1990, P134-146 Direct physical response from gold is extremely rare, because of the low grades in deposits, but indirect geophysical indications may occur because of its association with particular host rocks, marker beds, or structures with unusual properties. These various geological features, their specific attributes, and suitable geophysical techniques for their detection are reviewed. 92 refs.
:~) 1990 Pergamon Press pie. Reproduction not permitted