Kim Bo-Hyun, Larson Mark K, Lawson Heather E
Spokane Mining Research Division, NIOSH/CDC, Spokane, WA 99207, USA.
Int J Min Sci Technol. 2018 Jan;28(1):137-144. doi: 10.1016/j.ijmst.2017.10.003.
Bumps and other types of dynamic failure have been a persistent, worldwide problem in the underground coal mining industry, spanning decades. For example, in just five states in the U.S. from 1983 to 2014, there were 388 reportable bumps. Despite significant advances in mine design tools and mining practices, these events continue to occur. Many conditions have been associated with bump potential, such as the presence of stiff units in the local geology. The effect of a stiff sandstone unit on the potential for coal bumps depends on the location of the stiff unit in the stratigraphic column, the relative stiffness and strength of other structural members, and stress concentrations caused by mining. This study describes the results of a robust design to consider the impact of different lithologic risk factors impacting dynamic failure risk. Because the inherent variability of stratigraphic characteristics in sedimentary formations, such as thickness, engineering material properties, and location, is significant and the number of influential parameters in determining a parametric study is large, it is impractical to consider every simulation case by varying each parameter individually. Therefore, to save time and honor the statistical distributions of the parameters, it is necessary to develop a robust design to collect sufficient sample data and develop a statistical analysis method to draw accurate conclusions from the collected data. In this study, orthogonal arrays, which were developed using the robust design, are used to define the combination of the (a) thickness of a stiff sandstone inserted on the top and bottom of a coal seam in a massive shale mine roof and floor, (b) location of the stiff sandstone inserted on the top and bottom of the coal seam, and (c) material properties of the stiff sandstone and contacts as interfaces using the 3-dimensional numerical model, FLAC3D. After completion of the numerical experiments, statistical and multivariate analysis are performed using the calculated results from the orthogonal arrays to analyze the effect of these variables. As a consequence, the impact of each of the parameters on the potential for bumps is quantitatively classified in terms of a normalized intensity of plastic dissipated energy. By multiple regression, the intensity of plastic dissipated energy and migration of the risk from the roof to the floor via the pillars is predicted based on the value of the variables. The results demonstrate and suggest a possible capability to predict the bump potential in a given rock mass adjacent to the underground excavations and pillars. Assessing the risk of bumps is important to preventing fatalities and injuries resulting from bumps.
煤爆及其他类型的动力破坏一直是困扰全球地下煤矿行业数十年的难题。例如，仅在美国的五个州，1983年至2014年间就发生了388起可报告的煤爆事件。尽管矿井设计工具和开采实践取得了显著进展，但此类事件仍时有发生。许多条件都与煤爆可能性相关，比如当地地质中存在坚硬岩层。坚硬砂岩岩层对煤爆可能性的影响取决于其在地层柱状图中的位置、其他结构构件的相对刚度和强度，以及开采引起的应力集中。本研究描述了一项稳健设计的结果，该设计旨在考虑不同岩性风险因素对动力破坏风险的影响。由于沉积地层中地层特征（如厚度、工程材料特性和位置）的固有变异性很大，且确定参数研究时影响参数的数量众多，逐个改变每个参数来考虑每一种模拟情况是不切实际的。因此，为节省时间并尊重参数的统计分布，有必要开发一种稳健设计来收集足够的样本数据，并开发一种统计分析方法，以便从收集的数据中得出准确结论。在本研究中，利用稳健设计开发的正交阵列用于定义以下因素的组合：(a) 在块状页岩矿顶底板煤层顶部和底部插入的坚硬砂岩的厚度；(b) 在煤层顶部和底部插入的坚硬砂岩的位置；(c) 使用三维数值模型FLAC3D确定坚硬砂岩及其作为界面的接触的材料特性。数值实验完成后，利用正交阵列的计算结果进行统计和多变量分析，以分析这些变量的影响。结果，根据塑性耗散能量的归一化强度，对每个参数对煤爆可能性的影响进行了定量分类。通过多元回归，基于变量值预测塑性耗散能量的强度以及风险从顶板通过煤柱向底板的转移情况。研究结果证明并表明了预测与地下巷道和煤柱相邻的给定岩体中煤爆可能性的潜在能力。评估煤爆风险对于预防煤爆导致的死亡和伤害至关重要。
