Porosity in a puddled rice soil as measured with mercury-intrusion porosimetry

55A drainage occurs only by movement of dissolved gas. Localised consolidation and flooding of the gas bubbles complicates behaviour. 892031 Intergranular distribution of pore fluid and the nature of highangle grain boundaries in limestone and marble Hay, R S; Evans, B J Geophys Res V93, NB8, Aug 1988, P8959-8974 Natural and synthetic calcite rocks have been examined. On the basis of observation of wetting angle and electron microscopy, grain boundaries in calcite do not contain fluid layers. Pore water is probably confined to four-grain junctions or isolated pores along grain boundaries, and three-grain junctions. Interconnected pore fluid networks are unlikely to be stable. Mass transport at a grain size scale is unlikely to take place as fluid flow through a porous medium. Water or solutes may still have large effects on grain boundary diffusion rates, but will not be present as a separate phase along the boundary, although they will be dissolved in the lattice near the boundary. 892032 Porosity in a puddled rice soil as measured with mercuryintrusion porosimetry Guid, G; Pini, R; Poggio, G Soil Sci V145, N6. June 1988, P455-460 In situ determination of porosity and pore size distribution (PSD) is difficult. Mercury intrusion porosimetry was applied to a study of the modification of total porosity and PSD at different depths of a clay/silt/sand soil in which the soil structure had been broken down (puddling). The experimental technique is described. Results show advanced regeneration of the soil structure at final sampling, indicating puddling is temporary in this soil type. 892033 State-of-the-art in stochastic joint geometry modeling Kulatilake, P H S Key Questions in Rock Mechanics: Proc 29th US Symposium, Minneapolis, 13-15 June 1988 P215-229. Publ Rotterdam: A A Balkema, 1988 Published literature is reviewed. Delineation of statistically homogeneous structural regions and modelling of joint geometry parametersdoint orientation, joint intensity, joint trace length and size are considered. Joint geometry conceptual models are discussed, and weakness, contradictory and doubtful issues and validation of the proposed models considered. 61 refs. 892034 Design of soil pluviator for centrifuge testing Taylor, T; Meyer, M R; Fragaszy, R J Proc 24th Syrup on Engineering Geology and Soils Engineering, Coeur D'Alene, 29 Feb-2 March 1988 P191-200. Publ Washington: Washington State University. 1988 Pluviation of sand particles is a sample preparation method which simulates soil fabrics formed by natural cementation processes and provides homogeneous samples in a range of relative densities with good reproducibility. The design of a soil pluviator to prepare samples with near level surfaces, without the need for trimming or other post sample formation levelling techniques, for centrifuge testing is described. Initial trials and results for actual centrifuge test samples indicate accuracy of the apparatus.

892035 About the joint set intensity Grossman, N F Proc Symposium on Rock Mechanics and Power Plants, Madrid, 12-16 Sept 1988 VI, P41-47. Publ Rotterdam." A A Balkema, 1988 The intensity of a joint set quantifies the amount of rock fracturing due to that set without considering the individual joints. General formulae giving the intensity of a joint set as a function of its trace lengths on practical observation surfaces are presented. Statistical distributions of several correlated practical parameters of a set are evaluated. The scale effect on rock mass deformability is shown to be largely due to the skewed nature of joint distribution. Some reference is made to practical consequences of these observations. 892036 Preliminary geological and geotechnical study of lateritic weathering profiles derived from banded gneiss in the Ibadan area, S W Nigeria Adekoya, J A Proc Ninth Regional Conference for Africa on Soil Mechanics and Foundation Engineering, Lagos, Sept 1987 VI, P21-30. Publ Rotterdam: A A Balkema, 1987 Lateritic soils are not homogeneous, but made up of horizontal zones with differing characteristics. The geological nature and variation pattern of soil characteristics for the weathering profile of a banded gneiss are analysed. Field observations of exposures identified 6 morphologically distinct layers, top soil, stone layer, laterite, clay zone, saprolite and partly weathered rock. Preliminary laboratory tests on samples from 2 profiles to determine properties such as moisture content, Atterberg limits and dry density were undertaken. Results are presented.

Deformation and strength characteristics See also: 892197 892037 Undrained triaxial strength and stress-strain characteristics of a glacial till soil Atkinson, J H; Little, J A Can Geotech J V25, N3, Aug 1988, P428-439 Reconstituted and nominally undisturbed tubed samples of a lodgement till from Hertfordshire, UK, were tested. The soil is matrix dominant chalky boulder clay with little obvious engineering fabric. Crystalline calcite was evident in tubed samples. Test results were interpreted according to critical state soil mechanics, with different states and stress history taken into account, and showed a self consistent pattern. Reconstituted and tubed samples showed difference only at small strains, which may be attributed to cementation in tubed samples, broken down by reconstitution or at relatively large strains. 892038 Geotechnical aspects of seabed pits in the Grand Banks area Clark, J L; Landva, J Can Geotech J V25. N3, Aug 1988, P448-454 Seabed pits caused by iceberg scour have been studied to determine mechanisms of pit formation and ice loads transmitted to the seabed. Most of the pits are less than 3.5m deep and can be explained as indentation failures caused by rolling icebergs. The deeper pits cannot be explained in this manner and a two stage mechanism of grounding of an iceberg and subsequent transmission of wave loads to the seabed causing deepening of the pit is suggested.

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