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An analysis of current intersection support and falls in United States coal mines and recommendations to improve safety.

机译：分析美国煤矿当前的交叉路口支持和跌落，并提出改善安全性的建议。

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摘要

Background. The support of intersections in coal mines is an important safety issue in the U.S., as intersections are by far the most common area for unplanned falls of ground. A relatively comprehensive, nation-wide study of falls of ground is coupled with a national survey to mines about their support methods to determine common characteristics of failure and recommend changes to improve stability, and recommendations for future research.;Methods. Over 600 fall of ground reports were collected from nine of the 11 Mine Safety and Health Administration (MSHA) District offices, and data was compiled to determine common characteristics of these unplanned falls. Statistical analysis was conducted on the data to examine which variables affected fall dimensions. To obtain data on current support usage, mail and phone surveys were collected with responses from 70 underground coal mines, representing approximately 235 million tons of annual production, or 66% of the U.S. total. These surveys provided a national snapshot of what support mines are using as well as typical extraction height, intersection width, and other details. Rocscience's Phase2 software was used to model a typical coal mine intersection and examine possible stability changes with different support options.;Results. Surveys from underground mines revealed that the current industry average for intersection width is 20ft, average bolt length is 6ft, average distance from pillars to the first row of bolts is 3 to 4 ft, and a great majority of mines do not angle bolts over pillars. The fall of ground study confirmed that most falls are thicker than the average bolt length of 6 ft. and tend to be massive, extending past the intersection width of 20ft. The study also showed that falls with longer roof bolts installed typically had thicker falls which broke above the anchorage zone. Statistical analysis found a few questionably significant interactions, with the most prominent being the effect of roof type on fall height. Immediate roof geologies of dark shale and thinly laminated shale resulted in higher roof falls than other types. 2D modeling was unsuccessful at replicating the type of massive shear failures that have been commented on by MSHA personnel and that the study data suggests. It is the author's opinion that Phase2 and 2-D modeling in general may not be powerful or comprehensive enough to capture the true shear behavior of the rock strata in the roof beam because it cannot effectively model failure and dilation.;Conclusions. Increasing bolt length may not be the most effective solution to reducing massive intersection failures. Rather, installing angled bolts over pillars may increase the strength of the system at the crucial roof-pillar edge. Weathering of bolts and/or rock are likely contributing to the significant number of cutter failures happening months or years after excavation. Recommendations for future action include 3D modeling of cutter failure and benefits of angled bolts over pillars. More consistent and thorough MSHA 7000 50a forms will enable more accurate statistical analysis and a better understanding of massive failure characteristics.
机译：背景。在美国，煤矿十字路口的支撑是一个重要的安全问题，因为到目前为止，十字路口是计划外地面坠落的最常见区域。一项相对全面的，全国范围的地面塌陷研究与一项全国性的矿山调查有关，以了解矿山的支护方法，以确定破坏的共同特征，并提出改进稳定性的建议，并为今后的研究提供建议。从11个矿山安全与健康管理局（MSHA）地区办事处中的9个收集了600多个地面坠落报告，并收集了数据以确定这些意外坠落的共同特征。对数据进行统计分析，以检查哪些变量影响了跌落尺寸。为了获得有关当前支持使用情况的数据，我们收集了70个地下煤矿的邮件和电话调查，并做出了答复，这些煤矿的年产量约为2.35亿吨，占美国总产量的66％。这些调查提供了有关全国支持矿山使用情况以及典型开采高度，交叉口宽度和其他详细信息的全国快照。使用Rocscience的Phase2软件对典型的煤矿十字路口进行建模，并检查具有不同支持选项的可能的稳定性变化。来自地下矿山的调查显示，当前行业平均的交叉路口宽度为20英尺，平均螺栓长度为6英尺，从支柱到第一排螺栓的平均距离为3至4英尺，并且大多数矿山不会在支柱上倾斜螺栓。地面跌倒研究证实，大多数跌落都比平均6英尺长的螺栓厚，并且往往很大，延伸超过相交宽度20英尺。该研究还表明，安装了较长屋顶螺栓的瀑布通常具有较厚的瀑布，并在锚固区上方断裂。统计分析发现一些可疑的显着相互作用，其中最突出的是屋顶类型对跌落高度的影响。深色页岩和薄页岩的直接屋顶地质导致了比其他类型更高的屋顶跌落。 2D建模无法成功复制由MSHA人员评论过的大规模剪切破坏的类型，并且研究数据表明。作者认为，一般来说，Phase2和2-D建模可能不够强大或不够全面，无法捕获顶梁中岩层的真实剪切行为，因为它无法有效地建模破坏和膨胀。增加螺栓长度可能不是减少大量相交故障的最有效方法。相反，在支柱上安装成角度的螺栓可能会增加关键的顶柱边缘处系统的强度。螺栓和/或岩石的风化很可能导致开挖后数月或数年发生的大量刀具故障。对于未来行动的建议包括刀具故障的3D建模以及倾斜螺栓在支柱上的好处。更一致，更透彻的MSHA 7000 50a表格将使统计分析更加准确，并能更好地理解大规模故障特征。

著录项

  • 作者

    Mueller, Allen R.;

  • 作者单位

    Southern Illinois University at Carbondale.;

  • 授予单位 Southern Illinois University at Carbondale.;
  • 学科 Statistics.;Engineering Mining.
  • 学位 M.S.
  • 年度 2010
  • 页码 167 p.
  • 总页数 167
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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