364A
916264 Multilayer sampfing in the water-table region of a sandy aquifer Kaplan, E; Banerjee, S; Ronen, D; Magaritz, M; Machlin, A; Sosnow, M; Koglin, E Ground Water 1129, N2, March-April 1991, P191-198 A multilayer sampler (MLS) is described which enables vertical profiles of groundwater chemistry to be obtained with resolution of the order of a few centimetres. It incorporates dialysis membranes and can be used to determine concentrations of organic compounds, metals, and anions. Results are presented from its use in an unconfined sandy aquifer. Maximum concentrations of organic pollutants determined by the MLS were 4-40 times greater than those estimated on the basis of pumping tests.
916265 Sample disturbance of cemented collapsible soils Houston, S L; El-Ehwany, M d Geotech Engng Div ASCE 1/117, N5, May 1991, P731-752 Effects of sampling disturbance on response of collapsible soils have been investigated. Factors examined included tube length, sampler tube area ratio, driven or pushed sampling, and trimming or directly extruding the specimen into the ring. Response to wetting was very similar for block and hammered tube samples for well cemented, low gravel content soils. A small but statistically significant difference was seen for lightly cemented soils with low gravel content, probabably attributable to densification on tube sampling.
916266 Exploration drilling and reservoir model of Platanares geothermal system, Honduras, Central America Goff, F; Goff, S J; Kelkar, S; Shevenell, L; Truesdell, A H; Musgrave, J; Rufenacht, H; Flores, W J Volcanol Geotherm Res V45, N1/2, March 1991, P101-123
916268 Bucket auger modification for obtaining undisturbed samples of deep saprolite Stolt, M H; Baker, J C; Simpson, T W Soil Sci V151, N2, Feb 1991, P179-182 Although undisturbed samples of saprolite can be taken from walls of soil pits at relatively shallow depths, their recovery at greater depths has generally required clod or double cylinder methods. A simple modification to the bucket auger is described, which allows undisturbed samples of deep saprolites to be obtained, suitable for determination of physical properties or examination of microstructure.
916269 Developments in soft ground drilling Manby, C N D; Wakeling, T R M Tunn Tunnlg V23, N5, May 1991, P51-54 Advances in drilling, sampling, and in situ tests for site investigations in soft ground are discussed. Innovations to allow relatively undisturbed samples to be retrieved when cable percussion drilling, including those of cohesionless deposits below the water table, are first described. Reverse circulation rotary drilling allows sampling in unconsolidated and semiconsolidated ground. Standard, piezocone, and seismic cone penetrometers and Marchetti dilatometers can be used to profile mechanical properties, whilst neutron or gamma logs record density.
916270 Analysis of soil exploration of difficult Tupi subsoil for design Mehta, P; Desai, M D; Desai, H H Proc Indian Geotecimical Conference, 1989, Geoteclmiques of Problematic Soils and Rocks, Visakkapatnam, 14-16 December 1989 VI, P245-248. Publ New Delhi: Sarita Prakashan, 1989
Three diamond cored holes over 700m deep were drilled at the Platanares site, one in tuff/shale, one in metaconglomerate, one in andesite/shale/conglomerate. Two struck copious artesian geothermal fluids. Physical properties of the rock and temperature logs of the holes are described. Flow tests were carried out to investigate geothermal energy potential of the holes. Geochemical analysis was used to study the age of hydrothermal system and to evaluate potential problems of scaling of a geothermal energy system. A geological model of the reservoir was constructed.
Coastal flood deposits of the Tapi river delta show thin stratifications of sands and silts containing scattered lumps of clay, and have been subjected to leaching, changes of salinity, and desiccation over centuries. Wide areal investigation produces masses of data, whose analysis and investigation are complicated. The static CPT and vane shear test are limited in their suitability for use in the fine sands and silts. For simple foundation design it is suggested that dynamic CPTs over a restricted area provide adequate information within acceptable limits on time, ease of use, and economics.
916267 Optimization of grid-drilling using computer simulation Miller, J W Math Geol V23, N2, Feb 1991, P201-218
916271 Interpretation of sdf-boring and Im~iu prmmremeter tests Lacasse, S; D'Orazio, T B; Bandis, C Proc 3rd lnternatiatud Symposium on Pressuremeters, Oxford, 2-6 April 1990 P273-285. Publ London: Thomas Telford, 1990
Computer simulation of exploration drilling over a well known orebody is used to develop efficient drilling patterns for use in areas of similar geometry. Different patterns with different levels of follow-up were examined. Patterns of 100 drill holes in 10 fences at various spacings, each with 10 holes at various spacings, were simulated. Combinations of fence/hole spacing were compared as to their ability to hit large orebodies. Significant improvements are seen for one cycle of follow-up drilling.
A research programme aimed at assessing the test procedures, their usefulness, and the reliability of the derived soil parameters was set up at three different sites. Over a four year period the programme has used both self-boring and Menard pressuremeters. Several methods of interpretation have been developed. The results from this programme and recommendations on using similar equipment are presented.
© 1991 Pergamon Press plc. Reproduction not permitted