Study of strip-filling for old room and pillar mining goaf
According to the problems of land resources destruction and environmental pollution caused by the collapse of old room and pillar mining goaf, a goaf security evaluation model was established and applied to the safety assessment of a colliery in Ordos city. The results indicated that the room and pillar mining goafs in this coal mine area would fail with time passing. To solve the problems, with analyzing the structural characteristics and activation mechanism of old room and pillar mining goaf, based on the theory of strip mining, a new method of strip-filling for controlling subsidence of old room and pillar mining goaf was put forward and used in designing of the strip-filling plan of the colliery, the filling effect prediction have been worked out. It demonstrates that the strip-filling method is economically feasible.
The significance of in situ tests on large rock specimens
Abstract This paper reviews large scale in situ tests on rock conducted throughout the world. 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 ), the value and meaning of large scale in situ tests in compression are discussed. Practical guidelines are given for performing the tests, preferred testing techniques are described and typical data to be expected from the tests are listed. Empirical formulae are derived for the presentation of strength results and application of large scale test data to engineering design is demonstrated. It is also shown how the results of such tests can be directly applicable to predicting the behaviour of full size rock structures. Finally, the costs of large scale tests are considered, in terms of both time and money, and actual figures are quoted. It is concluded that large scale in situ tests can be an invaluable aid in engineering design and that their costs constitute a very small percentage of the value of production from an average mine and that the costs of tests are more than offset by the financial returns and technical gains obtained from large scale in situ tests.
EL TRATAMIENTO NEOPRAGMATISTA DE LA VERDAD EN RICHARD RORTY NEOPRAGMATIST TREATMENT OF TRUTH IN RICHARD RORTY
Richard Rorty, one of the most influential authors of our time, presents a critique of the philosophical concept of truth as correspondence. The conclusion of Rorty's neopragmatism is that the idea of truth as correspondence between language and facts is ineffective because it no longer works. The neopragmatist conception of truth indicates the only possible uses for the term «truthful,» revolving around the idea of jus - tification. In this article, the neopragmatist notion of truth is presented in order to