Platform orientation and start-up time during centrifuge testing

I I6A 854064 Permeability of compacted granular materials. Technical note Kenney, T C; Lau, D; Ofoegbu, G I Can Geotech J I,'21, N4, Nov 1984, P726-729 Permeability tests were performed on materials of differing grain size and shape of gradation. For the range of materials used, the test results indicate that permeability properties are primarily dependent on the size of particles in the fine fraction, and are essentially independent of the shape of the gradation curve. 854065 Laboratory evaluation of soil suction components Edil, T B; Motan, S E Geotech Test J V7, N4, Dec 1984, P173-181 A laboratory evaluation of the soil-water potential components (total, matrix, and osmotic suction) is presented using a series of clay specimens statically compacted dry- and wet-of-optimum. Test results indicate the use and limitations of the psychrometric method and the interrelationship of suction components. Osmotic suction is found to be measured most suitably on pore water extracts using psychrometry. 854O66 Effect of pressure on porosity and the transport properties of rock Walsh, J B; Brace, W F J Geophys Res I:89, NBll, Oct 1984, P9425-9431 Re-analysis of the flow model of Wyllie and Rose (1950) provides an explanation for the variance of transport properties with pressure. The mean hydraulic radius of the pore phase is calculated. The model is further developed by assuming microcracks to have rough surfaces of known topography, and that the decrease in transport properties with increased confining pressure is largely due to the closure of microcracks. The theory is illustrated by reference to experimental measurements. 854067 Porosity reduction and crustal pore pressure development Walder, J; Nur, A J Geophys Res V89, NB13, 10 Dec 1984, Pl1539-11548 A simple mathematical model is proposed showing the effect of porosity reduction on pore pressure development. The possible mechanisms of porosity reduction are discussed. Porosity, permeability and pore pressure in the crust may well be time dependent, even in regions not subjected to large deviatoric stresses. 854068

Reexamination of the constant head well permeameter method for measuring saturated hydraulic conductivity above the water table Reynolds, W D; Elrick, D E; Topp, G C Soil Sci V136, N4, Oct 1983, P250-268 There have been theoretical and practical improvements to the constant head well permeameter technique. The theoretical improvements give a new analytical solution which increases calculated hydraulic conductivity, providing results in good agreement with those measured using other techniques. Practical developments increase the efficiency and range of operation of the method. 854069 Air and water flow in a sealed, ponded vertical soil column: experiment and model Touma, J; Vachaud, G; Partange, J Y Soil Sci V137, N3, March 1984, P181-187

Laboratory experiments were conducted investigating ponded infiltration of a vertical column of soil, with air escape only through the surface and with air escape through the medium. In the first case air pressure reaches a constant value, independent of depth and time, which effects a decrease in water potential at the surface and lowers infiltration rate. A simple analytical model predicts cumulative infiltration when air pressure or water content at the soil surface is known. 854070 First integrals of the infiltration equation: 1. Theory Parlange, J Y; Fleming, J F Soil Sci V137. N6, June 1984, P391-394 Solutions to the infiltration equation may be obtained without iteration if it is assumed that diffusivity has a power law dependence on, and conductivity is proportional to, water content. For a particular dependence of surface flux on time, a solution that appears to be the only fully analytical solution for realistic diffusivity is obtained, and used to assess the accuracy of a very general optimisation technique~ 854071 Empirical relation for coefficient of permeability of sand Shahabi, A A; Das, B M; Tarquin, A J Proc 4th Australia-New Zealand Conference on Geomechanics, Perth, Western Australia, 14-18 May 1984 VI, P54-57. Publ Barton." lnst of Engineers, 1984 Constant head laboratory permeability test results on a number of mechanically-mixed sands are noted. Based on experimental results, a correlation between the coefficient of permeability, void ratio, effective size, and coefficient of gradation is presented. Auth. C o m p r e s s i b i l i t y , swelling and c o n s o l i d a t i o n See also. 854051, 854183, 854187 854072 Platform orientation and start-up time during centrifuge testing Bloomquist, D G; Davidson, J L; Townsend, F C Geotech Test J V7, N4, Dec 1984, P195-199 Two techniques are presented that improve the reliability of centrifuge testing of settling slurries. In the first, mechanical equipment modifications are described that allow a correct platform orientation to be achieved during flight. In the second, a simple mathematical equation is derived to account for the start-up period, during which the acceleration has not yet reached the final test level. Auth. 854073 Dynamic penetration resistance and the prediction o f the compressibility of a fine-grained sand - a laboratory study Clayton, C R I; Hababa, M B; Simons, N E Geotechnique V35, N1, March 1985, P19-31 Review of the factors which control the compressibility of sand and those which are thought to influence dynamic penetration resistance. Results of a laboratory study of the compressibility and dynamic penetration resistance of a uniform fine sand at a single density are presented. 854O74 Note on sedimentation and consolidation. Technical note Pane, V; Schiffman, R L Geotecludque I:35, N1, March 1985, P69-72