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  • Articles  (11)
  • strata control  (6)
  • geostatistics  (5)
  • Springer  (11)
  • American Meteorological Society
  • American Physical Society (APS)
  • De Gruyter
  • International Union of Crystallography
  • Springer Nature
  • Wiley
  • 2000-2004
  • 1995-1999
  • 1980-1984  (11)
  • 1935-1939
  • 1930-1934
  • 1984  (11)
  • 1959
  • 1937
  • Geosciences  (11)
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  • Articles  (11)
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  • Springer  (11)
  • American Meteorological Society
  • American Physical Society (APS)
  • De Gruyter
  • International Union of Crystallography
    • +
Years
  • 2000-2004
  • 1995-1999
  • 1980-1984  (11)
  • 1935-1939
  • 1930-1934
Year
Topic
  • 1
    Electronic Resource
    Electronic Resource
    Computer aided design and strata control (1984)
    Springer
    Geotechnical and geological engineering 2 (1984), S. 43-49 
    Details
    ISSN: 1573-1529
    Keywords: Coal mining ; strata control ; computer-aided design ; mine planning: steep seam working
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Summary Research into strata control has been pursued at Cerchar for the last 20 years, and has led to the definition of rules for the siting of new mine workings. These rules are drawn up as a function of the ‘volume of influence’ which is exerted by existing workings. To facilitate their application by the coal producer, a computer-aided design system for steep-seam faces has been developed on a minicomputer. The main features of the interactions which occur within the volume of influence of such faces are restated and the system which has been developed for design is described, with particular emphasis on the design stages which involved graphic systems and data base management.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00880856
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  • 2
    Electronic Resource
    Electronic Resource
    Use of rock classification to estimate roof caving span in oblong workings (1984)
    Springer
    Geotechnical and geological engineering 2 (1984), S. 133-140 
    Details
    ISSN: 1573-1529
    Keywords: Rock classification ; longwall mining ; strata control ; mine openings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Summary Indian coal measures have widely varying caving characteristics. The maximum roof span of a longwall or depillaring panel at the time of nether roof collapse is shown to have a direct relation withRQD from a study of 12 case histories. A similar relation between maximum unsupported span of openings and rock mass quality as defined by theQ-system was also demonstrated. A simple nomogram is presented to predict the face advance required to cause roof collapse when theRQD or rock mass quality is known.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00880878
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  • 3
    Electronic Resource
    Electronic Resource
    Validation and error analysis of a strata modelling technique (1984)
    Springer
    Geotechnical and geological engineering 2 (1984), S. 305-321 
    Details
    ISSN: 1573-1529
    Keywords: Coal mining ; finite difference analysis ; error analysis ; strata control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Summary Sources of error are investigated for a two-dimensional finite difference computer program designed to model strata deformation. The program calculates the displacements of a mesh of ‘mass points’, by the iterative solution of equations of equilibrium for the stresses acting on each mass point. The effect of errors on both displacement estimates and stress estimates is considered. Round-off errors are discussed analytically, while the effect of choosing too coarse a mesh density is demonstrated by comparison of two runs of the program with identical material properties, but different mesh densities. The influence of boundary conditions and the result of incomplete relaxation of the finite difference equations is estimated by comparison with Kirsch's analytical solution for a thin plate of finite width with a circular hole under unidimensional load. As a result of the analysis, estimators for stresses and displacements are derived, which make allowance for some of the sources of error; suitable boundary conditions for first and subsequent runs of the program are proposed; and a convergence criterion for the iterative process is suggested. These results are then applied to simulations of mining situations, together with various refinements of the basic model, such as separation and ‘slip’ between adjacent strata, and an allowance for failure of material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00881119
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  • 4
    Electronic Resource
    Electronic Resource
    Stochastic methods for the prediction of strata behaviour (1984)
    Springer
    Geotechnical and geological engineering 2 (1984), S. 291-304 
    Details
    ISSN: 1573-1529
    Keywords: Coal mining ; strata control ; finite difference analysis ; stochastic methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Summary A two-dimensional finite difference computer program, with the facility to represent stratified material by means of a mesh of ‘mass points’ with different material properties in each square of the mesh, is adapted to run on a mesh whose material properties are selected stochastically from a specified distribution. The program uses an iterative method to solve the equations of equilibrium, giving estimates of displacements and stresses. Lattices of normally distributed (zero mean, unit variance) random values are produced: lattices of statistically independent values and lattices whose values are spatially correlated, to give the effect of gradual variations resulting in regions of positive values and regions of negative values. These lattices are used to generate the material properties: Young's modulus, Poisson's ratio and density. Each property has a specified mean and standard deviation for each material in the model, and the precise values for each mass point are calculated from the relevant lattices. A simple model with a square opening is used to investigate the effect of this stochastic generation of material properties, by comparison of stresses and displacements near the opening for runs of the program with (1) deterministic and (2) stochastic properties. Similar lattices of random values are used to introduce a stochastic element in the criterion for failure of materials. This is applied to a more realistic simulation of a mining situation, where Mohr's Criterion is used, with a stochastic component, to determine whether failure has occurred at each point of the mesh.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00881118
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  • 5
    Electronic Resource
    Electronic Resource
    Comparison of geostatistical calculations with the results of open pit mining at the Iharkut bauxite district, Hungary: A case study (1984)
    Springer
    Mathematical geology 16 (1984), S. 173-191 
    Details
    ISSN: 1573-8868
    Keywords: geostatistics ; reserve evaluation ; bauxite prospecting ; open-pit mining
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Geostatistical calculations were carried out on two completely exhausted open-pit bauxite mines in the Iharkut bauxite district, Hungary. Fictitious regular drilling grids were laid on the maps, and horizontal variograms were calculated for drilling grids evaluating the bauxite surface, footwall surface, and bauxite thickness. Point kriging was carried out for all three parameters. Bauxite reserves were calculated using block kriging for bauxite thickness. The total estimation variance of the reserves has been established. Results were compared with real reserves obtained from the mine maps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01032215
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  • 6
    Electronic Resource
    Electronic Resource
    Conditional estimation variances: An empirical approach (1984)
    Springer
    Mathematical geology 16 (1984), S. 327-350 
    Details
    ISSN: 1573-8868
    Keywords: geostatistics ; estimation variance ; recoverable reserves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract One of the tasks routinely carried out by geostatisticians is the evaluation of global mining reserves corresponding to a given cutoff grade and size of selective mining units. A long with these recovery figures, the geostatistician generally provides an assessment of the global estimation variance, which represents the precision of the overall average grade estimate, when no cutoff is applied. Such a global estimation variance is of limited interest for evaluating mining projects; what is required is the reliability of the estimate of recovered reserves or, in other words, the conditional estimation variance. Unfortunately, classical linear geostatistical methods fail to provide an easy way to estimate this variance. Through the use of simulated deposits (representing various types of regionalization)the present paper reviews and discusses the effects of changes in cutoff grade and selective mining unit size on the conditional estimation variance. It is shown that, when the cutoff grade is applied to a pointsupport (sample-size)distribution, the conditional estimation variance appears to be readily accessible by classical formulas, once the conditional semivariogram is known. However, the evaluation of the conditional estimation variance seems to be less straightforward for the general case when a cutoff is applied to the average grade distribution of selective mining units. Empirical approximation formulas for the conditional estimation variance are tentatively proposed, and their performance in the case of the simulated deposits is shown. The limitations of these approximations are discussed, and possible ways of formalizing the problem suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01029885
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  • 7
    Electronic Resource
    Electronic Resource
    Cokriging of aquifer transmissivities from field measurements of transmissivity and specific capacity (1984)
    Springer
    Mathematical geology 16 (1984), S. 19-35 
    Details
    ISSN: 1573-8868
    Keywords: groundwater ; geostatistics ; cokriging ; kriging ; transmissivity ; specific capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract This paper presents a new application of the cokriging technique for constructing maps of aquifer transmissivity from field measurements of transmissivity and specific capacity. The technique is illustrated using data from Yolo Basin, California. Cokriging is well-suited for estimating undersampled variables. To improve the accuracy of the estimation, cokriging considers the spatial auto-correlation of the variable to be estimated and the spatial cross-correlation between the variable to be estimated and other, better-sampled variables. Consequently, in regions that lack data of the variable to be estimated, accurate estimation can still be made on the basis of auto- and cross-correlation. In addition, estimation variances can be obtained with a little additional computation effort.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01036238
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  • 8
    Electronic Resource
    Electronic Resource
    Kriging in a global neighborhood (1984)
    Springer
    Mathematical geology 16 (1984), S. 249-265 
    Details
    ISSN: 1573-8868
    Keywords: kriging ; moving neighborhood ; global neighborhood ; geostatistics ; automatic contouring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The kriging estimator is usually computed in a moving neighborhood; only the data near the point to be estimated are used. This moving neighborhood approach creates discontinuities in mapping applications. An alternative approach is presented here, whereby all points are estimated using all the available data. To solve the resulting large linear system the kriging estimator is expressed in terms of the inverse of the covariance matrix. The covariance matrix has the advantage of being positive definite and the size of system which can be solved without encountering numerical instability is substantially increased. Because the kriging matrix does not change, the estimator can be written in terms of scalar products, thus avoiding the more time-consuming matrix multiplications of the standard approach. In the particular case of a covariance which is zero for distances greater than a fixed value (the range), the resulting banded structure of the covariance matrix is shown to lead to substantial computational savings in both run time and storage space. In this case the calculation time for the kriging variance is also substantially reduced. The present method is extended to the nonstationary case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01032690
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  • 9
    Electronic Resource
    Electronic Resource
    Testing variograms for positive-definiteness (1984)
    Springer
    Mathematical geology 16 (1984), S. 407-421 
    Details
    ISSN: 1573-8868
    Keywords: variogram ; geostatistics ; positive-definite ; Bochner's theorem ; Hankel transforms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract A method based on Bochner's theorem is described for demonstrating the positive-definiteness of variogram models and for generating classes of valid variogram functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01029889
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  • 10
    Electronic Resource
    Electronic Resource
    Astrata control system and its application in West German coal mining (1984)
    Springer
    Geotechnical and geological engineering 2 (1984), S. 119-132 
    Details
    ISSN: 1573-1529
    Keywords: Coal mining ; strata control ; rock pressure ; mine planning ; longwall mining
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Summary Astrata control system has been developed to improve mine planning and design in deep coal mines in West Germany, where redistributed stresses from longwall workings in weak strata create difficult support problems. The system involves theoretical, laboratory and underground observations and studies of strata and support performance. Examples of the system covered in detail include planning the position and support of a cross-cut; improving a face layout; planning a gateroad; planning strata bolting and planning longwall face layouts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00880877
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