Direct shear testing of single joints under dynamic loading

137A 913062 Bearing capacity of footings on calcareous sands lsmael, N F; Ahmad, A H N Soils Found V30, N3, Sept 1990, P81-90 Drained triaxial tests and model tests on strip footings were used to determine compressibility and bearing capacity of two sands, a calcareous sand and a clean sand obtained by acid washing of the former. Compressibility was increased due to the presence of carbonates, peak strength parameters unchanged, and bearing capacity reduced. Various methods of analysis to account for the effect of compressibility on bearing capacity are discussed. 913063 Multiple regression analysis between the mechanical and physical properties of cohesive soils Hirata, S; Yao, S; Nishida, K Soils Found V30. N3. Sept 1990, P91-108 Two regression models representing the shear strength of soils are examined, the first based on Atterberg limits and the second on parameters of the Cam-Clay model. The basic concept is that mechanical properties are characterised by soil types and soil states. Data from natural and artificially mixed clayey soils are used. In both cases the multiple regression analysis was able to predict shear strength plus other strongly correlated parameters: unconfined compressive strength, deformability, and consolidation yield stress. The validity of the basic concepts is demonstrated by the results. 913064 Coupling analyses of limiting equilibrium state for normally consolidated and lightly overconsolidated soils Asaoka, A; Ohtsuka, S: Matsuo, M Soils Found V30, N3, Sept 1990, P109-123 In saturated soils, constitutive equations are generally considered in terms of effective stress, whilst external forces are in a state of equilibrium with total stresses. An additional field equation is required to link a velocity field to a pore pressure field. The problem is therefore treated as a coupling problem between the two fields. Both undrained and fully drained conditions are discussed. The following topics are analysed: undrained bearing capacity and excavation stability of soft clays: bearing capacity under partly drained and/or partly swelling conditions; seepage failure of fully drained loose sands; and rapid loading condition as compared to undrained condition. 913065 Estimation of weak floor strata properties and related safety factors for design of coal mine layouts Pula, O; Chugh, Y P; Pytel, W M Rock Mechanics Contributions and Challenges: Proc 31st US Symposium, Golden, 18-20 June 1990 P93-100. Publ Rotterdam: A A Balkema. 1990 Weak floor rocks (siltstones and mudstones) of thickness 0.62.0m are common beneath actively mined coal seams in Illinois. Representative mechanical properties for design purposes cannot be measured on exploration cores, but must be taken from plate loading tests or air drilled cores after mine development. An attempt is described to correlate bearing capacity and deformability of the floor rocks with index properties measured on exploration cores. Probabilistic and statistical treatment of data to obtain design values is presented.

913066 Low frequency acoustic emission from particulate matter Rubin, G F; Leach, M F Proc 4th Conference on Acoustic Emission/Microseismic Activity in Geological Structures and Materials, Pennsylvania, 22-24 October 1985 P131-142. Publ Clausthal-Zellerfeld." Trans Tech Publications, 1989 Elastic particles of simple geometric shape will respond to collision by oscillation in their natural mode of vibration, which will generate pressure waves through the surrounding medium. The influence of mean size,size distribution, shape and elastic properties of these particles on AE characteristics is analysed. Experimental results with spheres, discs, and cylinders of size range 10 microns to several ccntimetres are reviewed. The relatively low frequency content of the signals is most suitable for processing to determine characteristics of the materials. 913067 Direct shear testing of single joints under dynamic loading Barla, G; Barbero, M; Scavia, C; Zaninetti, A Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P447-454. Publ Rotterdam: A ,4 Balkema, 1990 Direct shear apparatus for testing joints under dynamic or static conditions is illustrated. It can hold samples up to 100mm in diameter. Preliminary tests and calibration are described. Static and dynamic test results on dry saw cut surfaces of Monticello sandstone are presented. Initial dynamic tests using a single shear load impulse indicate dynamic shear strength is highly strain rate dependent. 913068 LNEC experience on scale effects in the deformability of rock masses Cunha, A P; Muralha, J Proc 1st International Workshop on Scale Effects in Rock Masses, Loen, 7-8 June 1990 P219-229. Publ Rotterdam: ,4 A Balkema, 1990 Several deformability studies carried out by LNEC in schistous, granitic, and layered sedimentary rock masses have been re-analysed. Measurements were mainly by large flat jack, borehole dilatometer, or seismic refraction methods in the field, uniaxial and biaxial compression in the laboratory. Influence of specimen volume on measured deformability is illustrated. An understanding of associated scale effects is attempted, with due consideration given to influence of testing technique and sampling bias on variation and scatter of results. 913069 Deformability of a rock mass formed by an anisotropic rock and cut by a jointing system with orthotropic symmetry application of the theory to a real case Peres-Rodrigues, F Proc 1st International Workshop on Scale Effects in Rock Masses, Loen, 7-8 June 1990 P239-244. Publ Rotterdam: ,4 A Balkema. 1990 A theoretical description of deformability of a rock mass cut by a jointing system with orthotropic symmetry was proposed by Peres-Rodrigues in 1987. It has been tested using data from a metamorphic rock mass. In situ deformability measurements were made using large flat jack tests. Cores were taken for laboratory assessment of rock and joint parameters for input into the theoretical model. Results are discussed, and improvements, mainly concerning increased quantity and variety of input data, are suggested.

© 1991 Pergamon Press pie. Reproduction not permitted RMMS .~8 2 ~ M