187A the' inclusion of interface behaviour improves predictions of pillar strength, the yield criterion used in the analysis must be modified before in situ behaviour is accurately reproduced.
potential sources of rock burst. Results are consistent with observations in an iron ore mine in the Urals. Development of safe working systems for deep mines under such conditions is discussed.
913454 Model based on the minimization of strain energy as a tool in the design of coal pillars Hopkins, D L; Cook, N G W Rock MeelmMcs Contributions and Challenges: Proc 31st US Symposium, Golden, 18-20 June 1990 P177-184. Publ Rotterdam: A A Balkema, 1990
913458 Scale effects on underground excavations Fukushima, K Proc 1st International Workshop on Scale Effects in Rock Masses, Locn, 7-8 June 1990 1'209-217. Publ Rotterdam: A A Balkema, 1990
Empirical pillar design formulae have been successfully applied for many years, but extraction is now being undertaken under conditions outside those for which the formulae were developed. A model based on minimisation of strain energy is presented to describe stresses in coal pillars. A large open stope supported by pillars is modelled as two half spaces separated by rectangular arrays of identical rods. Deformation of pillar, roof, and floor, and mechanical interaction between pillars can be described. Stress in isolated pillars or arrays before yield can be calculated, and effects of pillar spacing or pattern evaluated. 913455 Fundamental experimental study of pillar behaviour Fry, M F; Hustrulid, W A Strata Control in Deep Mines: Proc ! ith Plenary Scientific Session of the International Bureau of Strata Mechanics, World Mining Congress, Novosibirsk, 5-9 June 1989 P3-1!. Publ Rotterdam: A A Balkema, 1990
Stress distributions were measured using the split platen technique in model pillars of salt, coal, limestone, and cement, each with different diameter/height ratios (D/H). For all but the cement pillars, the formation of a confined core was seen, with the sample becoming stiffer after initial failure and overall load bearing capacity increasing. For the cement pillars, load bearing capacity continued to decrease after failure. Formation of the confined core is considered to be dependent on D/H for specific rock types. The critical value can be determined with the techniques used in this work. 913456 Yield pillar design under strong roof, weak coal, and weak floor condition in US Iongwall mining - a case study Peng, S S; Tsang, P Strata Control in Deep Mines: Proc llth Plenary Scientific Session of the International Bureau of Strata Mechanics, World Mining Congress, Novosibirsk, 5-9 June 1989 P13-29. Pubi Rotterdam: A A Balkema, 1990 Finite element analysis including plastic and time dependent behaviour is used to examine the functions and performance of yield pillars. For the strong roof/weak floor condition, yield pillars should be used in conjunction with stiff pillars, the latter being large enough to carry the load transferred from the yield pillars. A method to determine yield pillar size is developed. Field data are provided from a West Virginia coal mine. 913457 Simulation and in-situ study of rock behaviour around mining opening approaching to a tectonic discontinuity Lihpin, Y I; Zoubkov, A Z Proc International Symposium on Rock Joints, Locn, 4-6 June 1990 P455-459. Publ Rotterdam: A A Balkema, 1990 Photelastic model tests were used to simulate a mining opening close to a longitudinal or transverse tectonic discontinuity, for the case of a deep mine. Changes in stress distribution and loading of the opening are considered with examination of
Conventional theory on size effects on underground excavations is presented and its shortcomings discussed. A new, three component theory is proposed. The constituents are: scale effect of stress concentrations using generalized Cosserat continuum theory to describe effects of microscopic inhomogeneity in rock; scale effects on rock and rock mass properties, taking into account Weibull theory: and effects of different construction sequence, chosen according to tunnel scale, on stress distributions. 913459 Stress cell measurements for the investigation of soil-pipeline interactions during vehicular loading Kohl, K M; New, B M; O'Rourke, T D Proc Conference on Instrumentation in Geotechnical Engineering, Nottinglmm, 3-5 April ! 989 V2. P 129-145. Publ London: Thomas Telford. 1989
Field trials to evaluate the performance of Kulite silicon pressure-diaphragm soil stress cells for monitoring distribution of soil stresses around a loaded pipeline are presented. Cell response was correlated with location of surface loads, trench geometry, and pavement conditions. Stresses measured away from the pipeline were consistent with those predicted by layered elastic theory, while those close to the pipeline were heavily influenced by its presence. 913460 Stresses, displacements and temperature around a circular opening in a thermo-elastic-plastic rock at great depth Ogawa, T; Lo, K Y Proc International Symposium on Rock at Great Depth, Pau, 28-31 August 1989 I/3. P1379-1391. Publ Rotterdam: A A Balkema, 1989 Closed form solutions for stresses and displacements around a circular opening containing a heat source in a thermoelasticplastic medium under an initial hydrostatic stress field are developed. The equation of equilibrium, compatibility conditions, and constitutive relations have been fully described in an earlier work (Ogawa and Lo, 1986). Influences of temperature, support, and rock mechanical properties on stress distributions, displacements, and strains are illustrated using parametric studies. Engineering consequences are discussed. 913461 Stress distribution around borehole in sandstone lkogou, S; Sibai, M; Skoczylas, F; Henry, J P Proc International Symposium on Rock at Great Depth, Pau, 28-31 August 1989 I/3. P1463-1470. Publ Rotterdam: ,4 A Balkema, 1989 Conventional triaxial tests using monotonous loading or loadunload cycles were carried out on Fontainebleau sandstone under various confining pressures. Interaction between pore pressure and matrix deformation is examined. Nonlinear behaviour and anisotropic dilatancy are essentially due to generation and closing of microfractures. Skeleton behaviour is modelled by a hypoelastic constitutive law and fluid-matrix
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