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Journal ArticleDOI

Stability, instability and design of pillar workings

TL;DR: In this article, the stability of pillar workings is discussed by generalizing the simple mechanism of the laboratory test to the mining situation, and it is proved that the workings will remain stable, regardless of the magnitude of the convergence experienced by the pillars, if the minimum slope of the load-convergence relations is greater than the smallest eigenvalue of K taken with a negative sign.
About: This article is published in International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts.The article was published on 1970-11-01. It has received 227 citations till now. The article focuses on the topics: Stiffness matrix & Rock mass classification.
Citations
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Journal ArticleDOI
TL;DR: In this paper, the authors present a review of the development of testing machines and a detailed discussion of the principles involved in controlling rock failure with stiff and servo-controlled testing machines.

267 citations

Journal ArticleDOI
TL;DR: In this article, a basic theory of damage mechanics was introduced to deal with the deformation of strain softening for rocks, and the effect of the damage threshold on the evolution of rock damage was analyzed based on this damage model.

188 citations

Journal ArticleDOI
TL;DR: In this paper, a survey of pillar performance was carried out to identify potential modes of instability, such as spalling of the hard brittle rocks, shearing along pre-existing angular discontinuities or progressive extrusion of soft infill materials on bedding planes.

165 citations


Cites background from "Stability, instability and design o..."

  • ...Inadequate regional stability can result in the collapse of multiple pillars over large sections of a mine, which can result in significant safety hazards [2,3]....

    [...]

Journal ArticleDOI
TL;DR: In this paper, the value and meaning of large scale in situ in situ tests in compression are discussed based on the authors' experience of 8 years of in situ testing involving 66 large coal speciments (up to 2 m in width and height and with width-to-height ratios from 0·5 to 3·4 ).

158 citations

Journal ArticleDOI
TL;DR: Six supervised learning algorithms, including linear discriminant analysis, multinomial logistic regression, multilayer perceptron neural networks, support vector machine (SVM), random forest (RF), and gradient boosting machine are evaluated for their ability to learn for PS based on different input parameter combinations.
Abstract: The prediction of pillar stability (PS) in hard rock mines is a crucial task for which many techniques and methods have been proposed in the literature including machine learning classification. In order to make the best use of the large variety of statistical and machine learning classification methods available, it is necessary to assess their performance before selecting a classifier and suggesting improvement. The objective of this paper is to compare different classification techniques for PS detection in hard rock mines. The data of this study consist of six features, namely pillar width, pillar height, the ratio of pillar width to its height, uniaxial compressive strength of the rock, pillar strength, and pillar stress. A total of 251 pillar cases between 1972 and 2011 are analyzed. Six supervised learning algorithms, including linear discriminant analysis, multinomial logistic regression, multilayer perceptron neural networks, support vector machine (SVM), random forest (RF), and gradient boosting machine, are evaluated for their ability to learn for PS based on different input parameter combinations. In this study, the available data set is randomly split into two parts: training set (70 %) and test set (30 %). A repeated tenfold cross-validation procedure (ten repeats) is applied to determine the optimal parameter values during modeling, and an external testing set is employed to validate the prediction performance of models. Two performance measures, namely classification accuracy rate and Cohen’s kappa, are employed. The analysis of the accuracy together with kappa for the PS data set demonstrates that SVM and RF achieve comparable median classification accuracy rate and Cohen’s kappa values. All models are fitted by “R” programs with the libraries and functions described in this study.

155 citations


Cites background from "Stability, instability and design o..."

  • ...Pillar stability is an essential prerequisite for safe working conditions in roomand-pillar mines (Salamon 1970; Ghasemi et al. 2014a)....

    [...]

References
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Book
01 Jan 1946

2,769 citations

Book
01 Jan 1965

2,118 citations

Journal Article
TL;DR: In this paper, the strength of coal pillars in South African collieries is derived based on data obtained from a survey of actual mining dimensions, which include information concerning both stable and collapsed areas of mining.
Abstract: A formula, which defines approximately the strength of coal pillars in South African collieries, is derived. The derivation is essentially empirical, based on data obtained from a survey of actual mining dimensions. The data include information concerning both stable and collapsed areas of mining. It is argued that the ratios of the predicted strengths to the calculated loads at failure, that is, the critical safety factors, form a frequency distribution. This distribution is centered around the safety factor of unity. The probability that a pillar will be stable is indicated by the ordinates of the cumulative distribution curve. This study assumes that the logarithm of the critical safety factor is normally distributed. It is postulated that the strength of pillars can be expressed, in the given range of dimensions, as a power function of the height and the width. The values of the three unknown parameters in this function, the constant multiplier and the powers of width and height, are estimated by the method of maximum likelihood. This method also gives an estimate of the logarithmic standard deviation of the distribution. The derived strength formula descriptionbes satisfactorily the information obtained from the survey of mining dimensions. The comparison of the derived results with those available in the literature shows no significant difference concerning the effect of pillar width. However, the influence of pillar height is found to be less than is estimated by previous authors.

275 citations

Journal ArticleDOI
TL;DR: In this paper, an analysis of the energy changes associated with the extension of Griffith cracks in tension and compression is made, which shows that the non-elastic behaviour can be described by a curved Griffith locus in the strain-stress plane.

242 citations