Statistic discriminant classification of jointed rock masses

Statistic discriminant classification of jointed rock masses

164A solid/solid medium with randomly distributed octagonal cylindrical inclusions is considered and the importance of multiple scattering between inc...

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164A solid/solid medium with randomly distributed octagonal cylindrical inclusions is considered and the importance of multiple scattering between inclusions is investigated using a finite difference numerical approach. The aim is estimation of elastic moduli and wave velocities from numerically generated observations for realistic constituent properties and study of the effect of inclusion distribution and shape. P and S wave velocities are computed for a number of inclusion filling factors.

Identification and classification See also: 933493

933195 C h ~ l c g t i o o of overlmrden properties for underground coal gasification: laboratory studies under high temperature and in situ stress conditions Wolf, K H A A; Hettema, M H H; De Pater, C J; Van Hooydonk, R Proc I S R M Symposhtm: Euroek'92, Chester, 14-17 September 1992 P99-104. Publ London: Thomas Telford, 1992 Roof rock above UCG cavities must withstand high temperatures and geomechanical and thermomechanical stresses. Samples of overburden claystone have been characterised in the laboratory before and after heating to temperatures up to 1400 deg C at 50 bar in nitrogen. Effects of the treatment on mineralogical, microstructural, and mechanical parameters are described. Classification parameters for the untreated and baked rock at ambient and high temperatures are evaluated using the schemes of Bieniawski and Hock and Brown. Cavity stand-up times are estimated.

933196 Design and support of inclined shafts through coal measures strata, the use of rock class/flcation Oldroyd, D C; Buddery, P S Proc I S R M SymposLum: Eurock'92, Cluster, 14-17 September 1992 P147-152. Publ London: Thomas Teiford, 1992

Coal mines in Natal are generally at shallow depth and reached by vertical or inclined shafts through Karoo sediments. Shaft design uses a rock classification system based on results of impact splitting, free swell, and slake durability tests. Weighted values from these tests are combined to define 5 rock classes, from very poor to very good. Support and some blasting practices are specified according to these classes. Two case examples of use of the classification are presented.

933197 Preliminary estimation of rock slope stability m ~ . rock mass ~ation systems Haines, A; Terbrugge, P J Proc 7th I S R M laterm~timud Co~,ress oR Rock Meckames, Aachen, 1620 September 1991 V2, P887-892. Publ Rotterdam: ~[ A Balkema, 1991 Classification schemes are often used at the preliminary stages of rock engineering projects. The Mining Rock Mass Rating (MRMR) scheme of Laubecher (1977) was originally developed in the mining industry to assess stability of underground excavations, but has now been extended for slope stability

applications. The use of the MRMR in design of slopes in a relatively homogeneous rock mass and in a range of heterogeneous rock units is presented. MRMR slope angles and those from rigorous analysis are compared. A chart is developed linking slope height, slope angle, and MRMR value, which is subdivided such that combinations for which rigorous analysis is desirable or essential are shown.

933198 Characterization of jointed rock masses for rock anchors Ebisu, S; Aydan, O; Komura, S; Kawamoto, T Proc Conference on Fractured and Jobtted Rock Masses, Lake Tahoe, 3-5 June 1992 P150-157. Pubi California: Lawrence Berkeley Laboratory, 1992 Anchor pullout tests and rock mass characterisation have been carried out at sandstone and granite sites. Distribution and geometry of the discontinuities were examined, elastic wave properties measured, and borehole jack tests carried out in the field. Physical and mechanical properties were measured on cores in the laboratory. RQD, maximum core length (MCL), and discontinuity number per lm length (DN) were evaluated. Correlations between the various geometrical, geophysical, mechanical, and empirical parameters have been studied, and their suitability for rock mass classification for anchor design is discussed.

933199 Statfmle tUmdmimmt ~ of joint~ reek masses Lin, Y M; Liu, X C Proe Conflreoce on Froctwted amf Yoksted Rock Masses, Lake Tahoe, 3-5 Jme 1992 P199-204. Publ California: Lawrence Berkeley Laboratory, 1992 A new classification method for rock masses is presented. This statistical method makes use of Fisher's discriminant analysis to establish a discriminant function for rock mass classification according to case history records and expert judgement. An optimal empirical formula is developed in terms of weighted values of UCS, joint spacing, and the square of the acoustic velocity ratio of rock mass and intact rock. Basic rock mass qualities can be adjusted to take into account effects of groundwater, field stresses, or geology.

933200 Charactedzafioo of weak, strafihd and clay bearing rock masses for engineering al~i~tions Ulusay, R; Ozkan, I; Unal, E Proc Comfereoce on Frocttwed amd Joimted Rock Masses, Lake Takoc, 3-5 J a e 1992 P233-240. Publ California: Lawrence Berkeley Laboratory, 1992

The Q and RMR systems widely used in mining and tunnelling will give misleading results if appl-h~d in weak, stratified, clay-bearing rock masses. A modified RMR system has been developed in Turkey for application in such rocks. Because of the difficulty in obtaining suitable cores for standard laboratory tests, point load tests are used to evaluate strength and anisotropy. A slake durability index term is included to take into account effects of groundwater. Parameters associated with condition of joints are weighted to represent the stratified nature and prvsence of clays, Applications of the original and modified RMR to design of slopes and underground excavations are shown.

© 1993 Pergamon Press Ltd. Reproduction not permitted