1、翻译部分英文原文25th International Conference on Ground Control in MiningTHE EVOLUTION OF INTELLIGENT COALPILLAR DESIGN: 1981-2006Christopher Mark, Chief, Rock Mechanics SectionNIOSH-Pittsburgh Research LaboratoryPittsburgh, PA, USAABSTRACT： The first International Conference on Ground Control in Mining ope
2、ned with the topic of pillar design. Two classic papers were presented, one by Bieniwski and the other by Wilson. Unfortunately, the two methods were so radically different from each other that it was nearly impossible to reconcile them. Adding to the confusion were the many other pillar strength fo
3、rmulas (such as the Salamon-Munro, the Holland-Gaddy, and the Obert-Duvall, just to name a few) that were also available. Little wonder that discussions of pillar design in those days often ended with anguished cries of “but which formula is the right one?” The past 25 years have seen substantial pr
4、ogress in the science of coal pillar design. Indeed, one testament to the improvement is the relative scarcity of papers on the topic at recent Conferences. Two factors have been largely responsible for the progress that has been made. The first has been the collection of large data bases of actual
5、case histories of pillar performance in a variety of settings, from shallow room-and-pillar mines through deep cover longwalls. These have made possible the development of empirical design procedures that are closely linked to real world experience. The second important factor is the development of
6、sophisticated computer models that can accurately simulate pillar behavior and roof/pillar/floor interactions. Together, these two lines of research have led to a new understanding of pillar mechanics that identifies three modes of pillar failure: Sudden, massive collapse, accompanied by airblast, f
7、or slender pillars (width/height4) Squeezing, or slow, non-violent failure, for most room and pillar applications (4w/h10)It is particularly satisfying that the insights gained from numerical models broadly support those obtained from the empirical studies. While far less controversial than in the p
8、ast, pillar design problems continue to arise. One recent example is pillar design for highwall mining. NIOSH has just released a software package, called ARMPS-HWM, which employs a number of modern pillar design concepts. Since highwall mining web pillars are long and slender, the greatest danger i
9、s that of a sudden collapse. ARMPS-HWM suggests two possible prevention strategies, one which concentrates on the SF of the webs, and the other which creates a “pressure arch” using properly sized barrier pillars. The paper will close with a discussion of some current needs in coal pillar design, in
10、cluding: Updating older empirical methods, such as ALPS, where changes in technology (new types of roof support, more demanding ventilation requirements, faster retreat rates) may have made some of the original case histories obsolete. Methods for determining site-specific coal strengths, focusing o
11、n bedding plane strength and other factors that may effect confinement, as input for both empirical and numerical design. Improved methods for evaluating coal pillar performance for environmental issues, such as surface subsidence and hydrologic impacts, which consider such factors as depth, w/h rat
12、io, water immersion/drainage, and time dependent seam strength. ACKNOWLEDGEMENT (AND APOLOGY) The topic of pillar design is one of the most important in the field of coal mine ground control, and the substantial progress that has been made has been due to the collective effort of many researchers an
13、d practitioners. In a brief overview like this one, it was only possible to mention a few of those who have made important contributions. As an apology to the many whose valuable work I was unable to include, I can only say that you are in very good company. INTRODUCTION Babcock et al. (1981), writi
14、ng in their survey paper for the First Conference on Ground Control in Mining, traced the science of pillar design all the way back to Coulomb in 1773. During the ensuing century, a variety of researchers tested rock specimens of a variety of sizes and shapes. However, it was not until 1911 that Bun
15、ting (1991) proposed the first true pillar design method for coal mines. Bunting described the necessity for pillar design this way: To mine without adequate pillar support will result, sooner or later, in a squeeze; the inherent effects of which are crushing of the pillars, caving of the roof, and
16、heaving of the bottom. In developing his formula, Bunting and his collaborators tested the strength of coal specimens in the laboratory and conducted back-analysis of full-scale pillar failures (“squeezes”) underground. Using essentially the same approach, a number of pillar design formulas were developed during the next 70
