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Borehole radar applied to the characterization of hydraulically conductive fracture zones in crystalline rock
IO1A 932230 Computer-based method to analyse information of urban engineering geological environmental quality for engineering geological mapping Yang, M; Fang, H Proc 6th International Congress International Association of Engineering Geology, Amsterdam, 6-10 August 1990, Symposia P79-86. Publ Rotterdam: A A Balkema, 1990 The application of engineering geological mapping to assist in land use planning and selection of appropriate construction technology is discussed. Data for computer assisted analysis should include geological and geotechnical details and information on likely development activities and their impact on the environment. Organisation of these details using database programs and application of techniques such as fuzzy mathematics in handling are considered. Some typical applications are presented: liquefaction potential analysis, foundation type selection, and soil strength mapping. 932231 Land subsidence in Shanghai - an application of the interaction between coastal-lowland geology and engineering geology Baeteman, C; Schroeder, C Proc 6th International Congress International Association of Engineering Geology Amsterdam, 6-10 August 1990, Symposia P191-199. Publ Rotterdam: A A Balkema, 1990 Groundwater overdraft has resulted in severe subsidence in Shanghai, with compaction of the top 70m and ground movement in excess of 3m. Geological,hydrological and engineering geological investigations were carried out to provide the framework of a numerical model for the subsidence. Emphasis is on the three dimensional nature of the sedimentary geology and sedimentary environmental interpretation including the effects of coastal processes. Geomechanical data are integrated into the geological framework with mechanical characteristics (in particular compressibility) assigned to each unit. 932232 Regional surveys of the continental shelf - the UK experience Long, D; Ardus, D A Proc 6th International Congress International Association of Engineering Geology Amsterdam, 6-10 August 1990, Symposia P289-294. Publ Rotterdam: A A Balkema, 1990 Systematic regional mapping of the offshore Quaternary geology of the UK has been carried out by the BGS using data collected in the period 1966-1986 by geophysical surveys, drilling, and sampling in water up to 2000m deep. Quaternary stratigraphy, Quaternary successions, and depositional environments have been determined. Geological features with implications for geotechnical properties are discussed: features resulting from periglacial processes, iceberg scouring, channelling, gas seepage, and slope instabilities.
Geophysical techniques See also: 932005, 932041 932233 Difficulties with phase spectrum unwrapping in spectral analysis of surface waves nondestructive testing of pavements A1-Hunaidi, M O Can Geotech J V29, N3, June 1992, P506-511 Spectral analysis of surface waves (SASW) is an established nondestructive technique for determination of pavement stiffness profiles. Case study details are presented of SASW examination of a service road (asphaltic layers/crushed stone/deep
clay). Inconsistencies were seen in the dispersion curve of the site when the usual procedures for unfolding the relative phase spectrum were used. A correction procedure for this is proposed and discussed. Application of the correction procedure gives SASW results closely matching those from crosshole tests and laboratory core examination. 932234 Resistivity of rook-salt in Asse (Germany) and petrophysical aspects Yaramanci, U; Flach, D Geophys Prospect V40, N1, Jan 1992, P85-100 The Asse mine is a site of research into radioactive waste disposal. A network of 180 permanently installed electrodes in various four-point configurations has been used to measure the resistivity of a future construction site for a test seal. The average resistivity of the almost homogeneous Stassfurt salt is about 0.6 megohm-m. There is a small anomaly due to a conductive intrusion, probably an anhydrite band. No anisotropy or change with time is seen to date. Pore water and its change can be estimated from the resistivities using Archie's equation with pore saturation included. 932235 Borehole radar applied to the characterization of hydraulically conductive fracture zones in crystalline rook Olsson, O; Falk, L; Forslund, O; Lundmark, L; Sandberg, E Geophys Prospect V40, N2, Feb 1992, P109-142 The RAMAC borehole radar system developed during the Stripa Mine project can be used in single-hole reflection, crosshole reflection, and cross-hole tomographic modes. The reflection modes provide geometric data on features some distance from the borehole. Absolute orientation of fracture zones can be obtained by combining single hole reflection data from adjacent holes. Similar methods have also been successfully developed for analysis of cross-hole data. The radar operates in the 20-60MHz range, has resolution of l-3m in crystalline rocks, and range in Stripa granite of about 100m (single hole) and 200-300m (cross-hole). Its accuracy is confirmed by geological and geophysical observations. 932236 Exploration in the basalt-covered areas of the Columbia River Basin, Washington, using electromagnetic array profiling (EMAP) Warren, R K; Srnka, L J Geophysics V57, N8, Aug 1992, P986-993 The EMAP method of collecting and processing magnetotelluric data has been tested at three basalt covered locations. Survey lines were located so as to intersect existing test wells. After EMAP filtering and inversion of the data, large and small structural features revealed near the holes closely matched those from electric induction logs. Details are revealed which are difficult to image in this terrain using seismic reflection methods. 932237 Detection of organic chemical contaminants by spectralinduced polarization method in glacial till environment Vanhala, H; Soininen, H; Kukkonen, I Geophysics V57, NS, Aug 1992, P1014-1017 The applicability of different geophysical techniques to mapping toxic waste spills depends on type of pollutant and geohydrological conditions at the site. The spectral induced polarisation method (IP) can be used to detect organic contaminants even in soils with very low clay mineral content, although it has to date primarily been used at clayey sites.
© 1993 Pergamon Press Ltd. Reproduction not permitted
Geophysical techniques See also: 932005, 932041 932233 Difficulties with phase spectrum unwrapping in spectral analysis of surface waves nondestructive testing of pavements A1-Hunaidi, M O Can Geotech J V29, N3, June 1992, P506-511 Spectral analysis of surface waves (SASW) is an established nondestructive technique for determination of pavement stiffness profiles. Case study details are presented of SASW examination of a service road (asphaltic layers/crushed stone/deep
clay). Inconsistencies were seen in the dispersion curve of the site when the usual procedures for unfolding the relative phase spectrum were used. A correction procedure for this is proposed and discussed. Application of the correction procedure gives SASW results closely matching those from crosshole tests and laboratory core examination. 932234 Resistivity of rook-salt in Asse (Germany) and petrophysical aspects Yaramanci, U; Flach, D Geophys Prospect V40, N1, Jan 1992, P85-100 The Asse mine is a site of research into radioactive waste disposal. A network of 180 permanently installed electrodes in various four-point configurations has been used to measure the resistivity of a future construction site for a test seal. The average resistivity of the almost homogeneous Stassfurt salt is about 0.6 megohm-m. There is a small anomaly due to a conductive intrusion, probably an anhydrite band. No anisotropy or change with time is seen to date. Pore water and its change can be estimated from the resistivities using Archie's equation with pore saturation included. 932235 Borehole radar applied to the characterization of hydraulically conductive fracture zones in crystalline rook Olsson, O; Falk, L; Forslund, O; Lundmark, L; Sandberg, E Geophys Prospect V40, N2, Feb 1992, P109-142 The RAMAC borehole radar system developed during the Stripa Mine project can be used in single-hole reflection, crosshole reflection, and cross-hole tomographic modes. The reflection modes provide geometric data on features some distance from the borehole. Absolute orientation of fracture zones can be obtained by combining single hole reflection data from adjacent holes. Similar methods have also been successfully developed for analysis of cross-hole data. The radar operates in the 20-60MHz range, has resolution of l-3m in crystalline rocks, and range in Stripa granite of about 100m (single hole) and 200-300m (cross-hole). Its accuracy is confirmed by geological and geophysical observations. 932236 Exploration in the basalt-covered areas of the Columbia River Basin, Washington, using electromagnetic array profiling (EMAP) Warren, R K; Srnka, L J Geophysics V57, N8, Aug 1992, P986-993 The EMAP method of collecting and processing magnetotelluric data has been tested at three basalt covered locations. Survey lines were located so as to intersect existing test wells. After EMAP filtering and inversion of the data, large and small structural features revealed near the holes closely matched those from electric induction logs. Details are revealed which are difficult to image in this terrain using seismic reflection methods. 932237 Detection of organic chemical contaminants by spectralinduced polarization method in glacial till environment Vanhala, H; Soininen, H; Kukkonen, I Geophysics V57, NS, Aug 1992, P1014-1017 The applicability of different geophysical techniques to mapping toxic waste spills depends on type of pollutant and geohydrological conditions at the site. The spectral induced polarisation method (IP) can be used to detect organic contaminants even in soils with very low clay mineral content, although it has to date primarily been used at clayey sites.
© 1993 Pergamon Press Ltd. Reproduction not permitted