دانلود رایگان مقاله انگلیسی انفجار زغال سنگ که در طول توسعه به وجود می آید: مهندسی مکانیک سنگ - الزویر 2018

abstract

Coal bursts are typically associated with highly stressed coal. Most bursts occur during retreat mining (longwall mining or pillar recovery) in highly stressed locations like the tailgate corner of the longwall panel. Others are associated with multiple seam interactions. However, a small but significant percentage of coal bursts have occurred during development or in outby locations unaffected by active mining. Most development bursts have been relatively small, but some have been highly destructive. No theory of coal bursts can be complete if it does not account for this type of event. This paper focusses on the development mining coal burst experience in the US, putting it into the context of the entire US coal burst database. The first documented development coal burst occurred almost exactly 100 years ago during slope drivage at the Sunnyside Mine in Utah. Sunnyside subsequently had a long history of bursts, mainly during retreat mining but also during development. Several Colorado mines have also experienced multiple development bursts. Many, but by no means all, of the development bursts in these western US coalfields have been associated with known faults. In the Central Appalachian coalfields, most development bursts have occurred in multiple seam situations. In some of these cases, however, there was no retreat mining in either seam. The paper closes with some lessons from this history, with implications for preventing such events in the future.

10. Conclusions

Development bursts provide an unusual perspective on the coal burst phenomenon. While a high level of stress is the one common characteristic of all coal bursts, development bursts by definition occur at lower stress levels then those encountered during retreat mining. In other words, if only the most highly stressed locations in a mine were liable to burst, then nearly all that mine’s retreat faces would burst before any of its development faces did.

Some of the development bursts described here also call into question the conventional wisdom regarding geology. The clearest examples are the bursts in the NFV of Colorado. There, the seams are sandwiched between at least 15 m of relatively weak roof and floor, yet the NFV has seen some of the most powerful bursts ever encountered in the US. Most of the largest bursts have been associated with relatively large seismic events, likely providing an important clue to their origins.

In fact, the frequency with which the presence of faults has been noted in conjunction with development bursts is striking. It is also surely significant that most fault-related bursts appear to have occurred in the seismically active western US rather than the seismically quiescent east. It seems likely that more faults in the west are critically stressed, and thus vulnerable to even very small mining-induced stress changes that may be triggered by development mining.