Publ Marshalltown: SANGORM, 1989 Mining at depths greater than 200 to 300m can produce con- siderable sidewall spalling since the stress on the edges of the pillars is greater than the
Trang 1912431
Analysis of collapses on tunnel construction sites on the new
lines of the German Federal Railway
Leichnitz W
Tunnlg Underground Space Technol I/5, N3, 1990, PI99-203
Most of the tunnels are through Triassic layers, Bunter Sand-
stones, shelly limestone, and Keuper series, whose characteris-
tics vary from hard.stable to completely softened Particular
difficulties arose in the Middle Bunter Sandstone, which has
high claystone content N A T M was the chosen construction
method Unexpected geological or hydrological conditions,
faulty application of shotcrete, late placement of support,
over-vigorous blasting, or change in lining flexibility on start-
up after breaks were associated with most collapses Examples
and remedial measures are illustrated
912432
Systematic sidewall support of coal pillars at depth
Lear C D; Hill R W
Proc Symposium on Advances in Rock Mechanics in
Underground Coal Alining, Witbank, 12 September 1989
P155-163 Publ Marshalltown: SANGORM, 1989
Mining at depths greater than 200 to 300m can produce con-
siderable sidewall spalling since the stress on the edges of the
pillars is greater than the strength o f coal in order to control
spalling, side wall support is required The consequences of
sidewall spalling and means of controlling it are discussed
Case studies based on two South African collieries are
outlined
912433
Predicting rock falls in an underground coal mine using
discriminant analysis and geostatistics
Kim Y C: Cervantes J A: Farmer 1 W
Proc 7th Annual Workshop Generic Mineral Technology
Center Mine @stems Design and Ground Control,
Blacksburg, 22-24 October 1989 P95-104 Publ Blacksburg:
Virginia Pol)'technic Institute and State Universio', 1989
The failure mechanism of horizontally layered rock above an
underground opening is dependent on the thickness of the
strata, state of stress, and the span to thickness ratio In order
to assess rock falls at Bessie coal mine in Alabama, the com-
bined effects o f the following factors were observed: presence
of finely laminated rock laminated rock thickness, pillar sizes,
slope of the seam bottom, overburden thickness, and surface
lineaments The use of geostatistical and statistical tools for
developing a model for predicting unstable conditions in min-
ing areas at Bessie is presented
912434
Wedge failure in a rectangular shaft
Pretorius, M J; Taljard J H
Proc Symposium on Rock Instability Problems in Mine
Shafts, Potchefstroom,lO May 1990 P29-36 Publ
Marshalltown: SANGORM, 1990
A technical analysis on the stability of the shaft sidewalls was
carried out by means of petroscope examination and a joint
analysis, after a wedge failure had occurred The joint analysis
program was implemented to determine whether more poten-
tially unstable wedges existed, and to calculate what the
probability of failure of such wedges would be Details of the
analysis and the design of supports needed to stabilise poten-
tial unstable wedges are discussed
117A
912435 Stability and failure of circular openings
Roegiers, R C
Proc International Symposium on Rock at Great Depth, Pau,
28-31 August 1989 V3, P1115-1122 Publ Rotterdam: A A Balkema, 1989
The status of the 1989 report for the US National Committee
on Rock Mechanics 'Stability, Failure and Measurements of Circular Openings' is summarised Features discussed are nat- ural and induced causes of failure, planning and sequencing o f construction, rock mass assessment, laboratory and field observations of failures of circular openings, analysis of sup- ported and unsupported openings, effects of discontinuities, and stability assessment
912436 Stability problems at great depth - applications to mine, tunnel and underground storage (In French)
Vouille, G
Proc International Symposium on Rock at Great Depth, Pau,
28-31 August 1989 V3, PI185-1189 Publ Rotterdam: A A Balkema, 1989
The instability at great depth of massive rocks close to under- ground cavities is connected to the development of fracture zones because of stress concentrations Modelling of post rup- ture behaviour in terms of plasticity with strain softening allows the development of this fracturing to be simulated either numerically or analytically, but this modelling must be improved to describe the explosive nature of certain strain Iocalisation phenomena and the kinetics of fracture propagation
912437
Instability problems at great depth drilling boreholes and wells
Guenot, A
Proc International Symposium on Rock at Great Depth, Pau, 28-31 August 1989 I/3, PI199-1208 Publ Rotterdam: A A Balkema, 1989
A typical case of deep borehole anisotropy from the Horda- land claystone-shale sequence in the North Sea is described Concepts of stability as relevant to deep boreholes are dis- cussed, and the need to be able to predict failure to allow pre- emptive remedial treatment is emphasised Key factors influ- encing stability are examined: formation lithology, depth, borehole inclination, and pore pressure Recent work to fur- ther understanding of borehole stability is summarised, cover- ing rock rheology models and parameters, influence of discontinuities, and the mechanical effects of the drilling fluid
912438 Predictions of wellbore stability in shale formations at great depth
Steiger, R P; Leung, P K
Proc International Symposium on Rock at Great Depth, Pau, 28-31 August 1989 V3, P1209-1218 Publ Rotterdam: A A Balkema, 1989
Most wellbore stability problems arise in shales Major improvements in wellbore stability and shale technology are required to significantly lower costs for today's complex drill- ing programs Recent work is summarised Empirical and model predictions of mechanical and chemical stabilisation are examined Shale research into effective stress control on shale strength, pressure dependent elasticity, unconfined compres- sion strength, and the development of a shale database are
described An advanced stability model is outlined and regions for further study are identified
~, 1991 Pergamon Press plc Reproduction not permitted