Hydraulic conductivity assessment of slurry wall using piezocone test

SURFACE STRUCTURES:BASE Coir geotextiles play a major role in geotechnical engineering which covers foundations, earth structures, roads, dams and canals etc. Acceptance of coir geotextile in India is slow. Most of the civil engineers, public authorities and contractors are not aware of the potential and performance of coir geotextile. On the other hand, the coir manufacturers are not aware of the civil engineering requirement. The coir geotextile can be realised only through application development and participation of the textile industry in the related research is of vital importance. (from Author) 956233 Hydraulic conductivity assessment of slurry wall using piezocone test M. Manassero, Journal of Geotechnical Engineering - ASCE, 120(10), 1994, pp 17251746. Cone-penetration tests with pore pressure measurement or piezocone tests (CPTUs) are carried out inside a cutoff wall for polluted groundwater containment. The backfilling material for the cutoff wall is a typical cement-bentonite selfhardening slurry whose composition is 76.8% water, 19.2% blast furnace cement, and 4% sodium bentonite. A tentative framework for interpretation of CPTUs in terms of hydraulic conductivity is developed. In particular, a continuous assessment of hydraulic conductivity along a vertical profile is attempted by combining the piezocone penetration parameters. The test results indicate that the CPTUs are a.promising tool for in-situ quality control of cutoff walls in terms of evaluating the actual hydraulic conductivity of the completed cutoff wall and, to some extent, of detecting and locating hydraulic defects that, in many cases, are the main causes of poor in-situ performance. (from Author)

Soil stabilisation 956234 Effects of intervening media on dielectrophoretic strengtbening of soft clays K. Y. Lo & J. Q. Shang, Canadian Geotechnical Journal, 31(S), 1994, pp 607-613. The process of dielectrophoresis has been shown to be applicable for soil improvement. This paper presents the results of continuous investigation into factors a&&rig dielectrophoretic strengthening of soft clays. The results indicate that the increase in undrained shear strength and decrease in soil water content after a dielectrophoretic treatment are dominated by the type and water content of intervening media. By mimmizing the space between soil and electrode and adapting a clay slurry of relatively low water contents as the medium, the process of dielectrophoretic strengthening can be enhanced. (from Authors)

Soil compaction 956235 Equivalent diameter of vertical drains with an oblong cross section R. P. Long & A. Covo, Journal of Geotechnical Engineering ASCE, 120(9), 1994, pp 1625-1630. The availability of wick drains has rapidly led to their replacing conventional sand drains as a means of accelerating the consolidation of soft soils. Wick drains have an oblong shape, but the available theories of radial consolidation have been derived for drains having a circular shape. The equivalent diameter of oblong drains is determined with an analog field plotter. The results of all methods are reviewed and then compared to published experimental values of eqivalent diameters of wick drains. Values of equivalent drain

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diameters backfigured from field data are discussed with respect to the influence of smear. (Authors)

Ground freezing 956236 Ground freezing and sampling of foundation soils at Duncan Dam D. C. Sego, P. K. Robertson, S. Saaitharan, B. L. Kilpatrick & V. S. Pillai, Canadian Geotechnical Journal, 31(6), 1994, pp 939-950. In situ ground freezing to obtain undisturbed samples of a loose sand beneath the Duncan Dam in British Columbia is described. Once frozen, the sand was cored and brought to the surface using a Cold Regions Research and Engineering Laboratory core barrel, used extensively in permafrost regions. The design, installation, and performance of the liquid nitrogen freezing systems are described in detail. The drilling, sampling, and preparation of the frozen core for transport to the testing facility are also outlined. The quality of the core retrieved during the sampling was judged to be excellent, and good agreement was found between the void ratios measured using both the frozen core and highquality gamma-gamma density logging techniques, which were performed adjacent to ground-freezing and sampling locations. (from Authors)

SURFACE STRUCTURES General 956237 Concept of the transport system in the western part of the Arctic A. F. Parfenov, Hydrotechnical Construction, 28(3), 1994, pp 138-142; translated from: Gidrotekhnicheskoe Stroitel’stvo, 3, 1994, pp 17-22. In view of increasing development of oil and gas resources offshore Russia, this article discusses potential exports, pipeline transport systems, and sea transport routes. Geotechnical aspects, climate and ice conditions, and port developments are described. (J.M.McLaughlin)

Base courses and pavements 956238 Digital image processing as a tool for pavement dhtress evaluation A. Georgopoulos, A. Loizos & A. Flouda, ISPRS Journal of Photogrammetry & Remote Sensing, 50(l), 1995, pp 23-33. In this paper a method developed jointly by the Laboratories of Highway Engineering and Photogrammetry of the National Technical University of Athens is ‘described and proposed. The method involves digital image processing techniques to provide suitable digital imagery as input to specialised software developed especially for this project. This software determines objectively and fully automatically the type, the extent and the severity of surface crack&s for flexible road pavements. The proposed method presented substantial agreement, when compared with sy&.ernatic visual ratings of existing pavement trackings carried out according to the internationally accepted requirements for airfield and road pavement of the Federal Aviation Administration (FAA). (from Authors)