Textural segmentation of digital rock images into bedding units using texture energy and cluster labels

PROPERTIES:COMPOSITION, STRUCTURE, DENSITY aquifer were demonstrated to be identical to those estimated by Bear and Corapcioglu. -from Authors

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saprolites and desert sediments; and slope stability. A brief synopsis of each paper is provided. -R.Gower

Composition, structure texture and density Measurement of water pressure and its effects

945035 A column study of static nonequilibrium fluid pressures in sand during prolonged drainage S. L. Barbour & E. K. Yanful, Canadian Geotechnical Journal, 31(2), 1994, pp 299-303. In the design of layered soil systems, such as the design of liners or covers over unsaturated soil, a key design concern is the magnitude of negative fluid pressure that will develop along the base of the liner or cover. In the absence of evaporation or vapour migration, the maximum negative fluid pressures will develop near the cessation of dra{nage. Previous theoretical analyses and numerical modelling of these systems have indicated that this pressure will be the pressure at which an underlying sand reaches its residual water content. The hydraulic conductivity of the sand at these pressures is so small that 'static' nonequilibrinm pressures are sustained over long periods of time. In this note, laboratory verification is provided for the magnitude of these pressures based on drainage of a fine and coarse sand column. -Authors

PROPERTIES OF ROCKS AND SOILS

945038 Tonminerale und Bodenmechanik im Gunzesrieder Achtal: Untersuchungen an Boden und deren Substraten, der Faltenmolasse und des Flysch im Oberallgau (Clay mineralogy and soil mechanics in the Gunzesried Valley: investigations into the soils and their substrata of the faltenmolasse and flysch in Oberallgau) J. Schutz, Mannheimer Geographische Arbeiten, 37, 1994, 135 pp, price D M 20.00. The geology of the area is re~resented by Tertiary and C ~ taceous sedimentary rocks ('Faltenmolasse und Flysch ). The parameters affecting plasticity and shear strength can be isolated, the relations can be formulated mathematically using multiple regression-statistics. Examples illustrate the strong influence of clay mineralogy of softs and sediments on soil mechanics. Spatial statistics were used to define the influence of soft plasticity, among other natural parameters, on slope stability. -from English summary 945039 Strain and fabric analyses based on p o r p h y r o . clast interaction B. Tikoff & C. Teyssier, Journal of Structural Geology, 16(4), 1994, pp 477-491. Two-dimensional computer models of the interaction of elliptical clasts in a variety of kinematic conditions are used to study how clast imbrication and shape fabric development relate to strain and strain history. The models provide templates, for a known clast density and clast e.llipticity, that correlate clast imbrication, angle of collision and clast shape fabric to strain and kinematics of deformed rocks. Modeling also shows that the mode of clast interaction plays a significant role in the accumulation of imbricated clasts and the development of shape fabric. Based upon the mode of clast and train rotation (using the March rotation of passive lines and the Jeffery rotation of rigid particles as end-members), three models are defined in an attempt to simulate the conditions of clast interaction under varying conditions. -from Authors

945036 Reviving the mission of rock mechanics teaching in mining and civil engineering Z. T. Bieniawski, International Journal of Rock Mechanics & Mining Sciences, 31(2), 1994, pp 135-142. The author performed a study involving mining and civil engineering undergraduate programs in the USA and Europe, and concluded that rock mechanics teaching is out o f date with the educational issues of today, that the material taught is infrequently updated, that the teaching techniques have hardly changed, that little attention is paid to engineering design in rock mechanics while sopl~isticared computer analyses and laboratory testing predominate. Recommendations are made about what steps should be taken urgently to salvage the teaching of rock mechanxcs. -from Author

945040 Textural segmentation of digital rock images into bedding units using texture energy and cluster labels S. M. Luthi, Mathematical Geology, 26(2), 1994, pp 181-196. The texture of digital rock images, as recorded, for instance, with borehole imaging devices, is shown to reflect different bedding types. Textural segmentation of borebole images, therefore, subdivides the recorded sequence into bedding units. A textural segmentation algorithm based on the concept of 'texture energy' achieves .~ood results when compared with synthetic as well as real ate. Texture energy revolves filtering of the original ~mage with a set of texture sensitive masks. The filtering is done as a finite convolution over the size of the masks. A recurring and relatively ftl-defined problem in this field are macro-textures, i.e., the cyclic interbedding of two or more bedding types. Sliding Fourier transforms and variable mask scale can successfully address the zonation of macro-textures. -from Author

945037 General r e p o r t on tropical and residual soils G.E. Blight, in: Geotechnics in the African environment. Vol. 2, ed G.E. Blight & others, (Balkema), 1994, pp 443-457. Initially the working definitions of tropical and residual softs are given,, along with examples and their common uses (eg saprolnes and laterites). Common geotechnical problems encountered when using tropical and residual softs, including unsaturation, slope stability, shatlow foundations, raft and spread foundations and deep foundations, are covered. 13 papers on residual and tropical soils were submitted, and are grouped into 4 sections: expansive phenomena; later/tic and pedogenic softs and roads;

945041 C a r a c t e r i z a c a o geotecnica de urea argila mole do Recife (Geotechnical characterization of a recife soft clay) R. Quental Coutinho, J. T. Romao De Oliveira & F. A. Brasil Danziger, Solos e Rochas, 16(4), 1993, pp 255-266. About 50% of the metropolitan area of the city of Recife is founded on deposits of organic soft clays. Due to its high compressibility and low shear strength it usually presents serious problems to foundation engineering. This paper presents results of an investigation of laboratory tests and m sltu tests that were performed in one of the deposits of Recffe soft clays. The selected site has been previously studied by some researchers and is located in the area of the Clube Intemacional. Results from the present investi-