Application of coal mine roof rating in Chinese coal mines

The coal mine roof rating(CMRR) is a measure of roof quality or structure competency for bedded roof types typically of underground coal mines. The CMRR has been used widely in the US, South Africa,Canada and Australia. In order to investigate the application of the CMRR system in Chinese coal mines,two coal mines in China located in Panjiang Coal Field in Guizhou Province were investigated. Field data were collected which is required to calculate the CMRR value based on underground exposure. The CMRR values of 11 locations in two coal mines were calculated. The investigations demonstrated that the chance of mine roof failure is very low if the CMRR value is more than 50, given adequate support is installed in mine. It was found that the CMRR guideline are useful to preliminarily investigate stability in Panjiang Coal Field mines.

Investigation of factors influencing roof stability at a Western U.S.longwall coal mine

The coal mine roof rating(CMRR) was developed to bridge the gap between geological variation in underground coal mines and engineering design. The CMRR accounts for the compressive strength of the immediate roof, the shear strength and intensity of any discontinuities present, and the moisture sensitivity of the immediate roof. The CMRR has been widely used and validated in Eastern US coal mines, but it has seen limited application in the Western US. This study focuses on roof behavior at a Western coal mine(Mine A). Mine A shows significant lateral geological variation, along with localized faulting and a laterally extensive sandstone channel network. The CMRR is not used to predict roof instability at the mine. It is, therefore, hypothesized that there are other factors that are correlated with roof instability in underground coal mines that could potentially also be considered in conjunction with the CMRR.This hypothesis was tested by collecting 30 CMRR measurements at Mine A. At each measurement location, a binary record of the roof condition(stable or unstable) was made, and other parameters such as depth of cover, presence of faulting, and sandstone channels were also recorded. ANOVA tests showed that the CMRR values and the roof conditions were not strongly correlated, indicating that the CMRR input criteria are not fully predictive of roof stability at this mine. The CMRR values showed statistically significant correlations(p less than 0.05) with faulting as well as with location at an intersection. For areas that had previously experienced roof fall but were currently stable, faulting was correlated with roof condition(p less than 0.05) only when the condition was classified as unstable.

Overburden fracture evolution laws and water-controlling technologies in mining very thick coal seam under water-rich roof

Considering the danger of water inrush in mining very thick coal seam under water-rich roof in Majialiang Coal Mine,the universal discrete element(UDEC)software was used to simulate the overburden fracture evolution laws when mining 4#coal seam.Besides,this study researched on the influence of face advancing length,speed and mining height on the height of the water flowing fractured zones(HWFFZ),and analyzed the correlation of face advancing length and change rules of aquifer water levels and goaf water inflow.Based on those mentioned above,this research proposed the following water-controlling technologies:draining the roof water before mining,draining goaf water,reasonable advancing speed and mining thickness.These water-controlling technologies were successfully used in the feld,thus ensured safely mining the very thick coal seam under water-rich roof.

Analysis of Roof Failure at the Intersections on a Coal Mining

The objective of this paper is to understand the behavior of the roof and the cause of roof failure of a coal mining. Eleven roof falls occurred in the mine section in sequence. All the roof falls were surveyed, and the geological features were determined which include rock type, mechanical properties, and thickness. The immediate roof thickness was interpolated to determine the cause of the roof failures which was the inappropriate roof support where the immediate roof is thicker. The average thickness of the immediate roof was determined by the drilling log in 1.2 m (3.9 ft.). The roof support was design based on the average thickness, and the bolt length is 1.5 m (4.9 ft.) in suspension. The challenge was to estimate where the immediate roof gets thicker and to design the support considered to maintain the regular bolt length. This is because the cost and productivity of support operation could increase if the bolt length changes as the roof thickness changes. The idea was to adjust the support for beam building with a fully grouted bolt and rearrange the bolt geometry to keep the roof stable. It means, with the same bolt length the type of roof support would change from suspension to beam building depending on when the roof gets thicker. Two empirical approaches were considered to design the roof support: 1) CMRR and 2) RMR. The entry width is 5 m and the roof support was designed with four bolts per row. Where the roof support must change to beam building, the number of bolts per row changes to five or six. The results of the design and application on underground showed that the approach keeps stable.

基于组合赋权三维云评估技术的深部煤矿顶板事故风险分析

为了更好地对深部煤矿顶板事故展开风险评价,提出了组合赋权三维云评估技术。基于事故统计及事故致因理论,对深部煤矿顶板事故风险指标体系展开研究,采用博弈论对改进层次分析法(Analytic Hierarchy Process,AHP)和熵权法进行博弈分析,以实现风险指标的组合赋权,通过构建三维云模型,对深部煤矿顶板事故危险性进行可视化分析。结果表明:包括行为、技术、设备、环境、管理5大风险因素在内的一级指标并其下20个二级风险指标是深部煤矿顶板事故风险评价指标体系的主体内容,且以环境风险权重最大;由三维云评估技术分析可知,平煤九矿的顶板事故风险级别为Ⅲ级,即修复后可接受,与该矿生产实际情况相符。组合赋权三维云评估技术的提出有助于完善深部煤矿顶板事故风险评价方法,可应用于工程实践。

一种煤矿顶板灾害防治知识图谱构建方法

目前煤矿顶板灾害防治措施决策及事故原因分析等过程主要依赖人工经验,智能化水平较低。顶板灾害防治知识图谱可整合顶板灾害防治知识和经验,辅助顶板灾害事故原因分析和顶板灾害防治措施决策。提出了一种煤矿顶板灾害防治知识图谱构建方法。采用本体方法完成煤矿顶板灾害防治知识建模,将顶板灾害防治领域的概念分为矿井地质类、开采技术类、防治措施类和事故表征类,将概念之间的关系定义为使用、引发、易发、治理、预防和适用,为煤矿顶板灾害防治知识抽取(实体抽取和关系抽取)奠定基础;结合煤矿顶板灾害防治领域文本存在大量嵌套实体和关系之间存在实体重叠的特点,确定了基于跨度的实体抽取方法和基于依存句法树引导实体表示的关系抽取方法;构建了顶板灾害防治领域语料库,采用Neo4j图数据库存储数据,为顶板灾害防治知识图谱的应用提供数据来源支撑;展示了煤矿顶板灾害防治知识图谱局部构建结果,说明该知识图谱可辅助顶板灾害事故原因分析和防治措施决策,从而提高顶板管理的智能化水平;指出基于该知识图谱,结合自然语言处理和知识推理等技术,可实现顶板管理知识问答。

深埋复合顶板煤巷离层失稳机理及控制研究

为探究深埋复合顶板煤巷离层失稳及控制机理,以淮南某矿1692(1)运输顺槽为工程背景,原位观测并分析巷道顶板变形破坏特征及原支护效果,基于材料力学原理建立复合顶板岩层力学模型,解析复合顶板各分层挠度表达式,揭示复合顶板离层失稳机理,并探究全长锚固和锚索对复合顶板离层控制机理,提出全锚改性-长锚索组合联合支护技术。研究结果表明:联合支护利用全长锚固增加复合顶板底层的弹性模量,使复合顶板底层挠度下降,通过锚索将复合顶板各分层组合成整体,形成组合梁结构,使复合顶板整体挠度降低,现场监测表明顶底板移近量下降64%,顶板未发现离层现象,最大裂隙深度由8.1 m降低至3.8 m,降低53.80%,煤巷的稳定性得到显著提升。研究结果可为深埋复合顶板离层垮落失稳控制提供借鉴。

矿井采煤工作面顶板事故防治策略研究

随着中国采煤工作面深度和开采规模不断扩大,顶板事故不断增多,给矿井生产带来了极大的影响。如何有效防治顶板事故,成为了亟须解决的问题。论述了矿井采煤工作面顶板事故防治的重要性,通过对事故成因的分析,提出了相应的防治策略,通过对比,证实了研究方向的准确性,可以为矿山安全生产提供有益的参考。

基于随机森林算法的煤巷顶板位移预测与应用

煤巷围岩稳定控制是保障煤矿安全高效开采的关键,煤巷顶板位移量是反应煤巷围岩稳定性的关键指标,本研究提出机器学习方法对煤巷顶板位移进行超前预测研究。确定了煤巷顶板位移的8个重要影响指标,建立了煤巷顶板位移预测数据库并对数据进行了指标相关性和重要性分析。基于RF、GA-SVM和GA-ANN分别建立了三种煤巷顶板位移预测模型,选用RMSE、MAE和R2三个指标来评价模型的性能。结果显示,RF模型测试性能最佳,R2=0.909,RMSE=20.475,MAE=16.790,GA-ANN模型的性能最差。采用十折交叉方法对RF模型和GA-ANN模型进行可靠性验证,结果显示RF模型的稳定性更高,平均R2为0.891。将RF模型应用到干河煤矿2-1121巷,预测值与实际值的绝对误差为19 mm,相对误差为11.18%,说明了RF模型对煤巷顶板位移预测的准确性与可靠性,研究结果对煤巷顶板位移预测提供了一种新途径。

近浅埋多层厚硬顶板大采高综放工作面矿压显现规律研究

针对榆神矿区近浅埋多层厚硬顶板条件下,“大周期”来压支架立柱下缩量大、煤柱应力集中系数高、稳定性差等强矿压问题,采用了数值计算、微震和煤体应力监测等技术手段,对覆岩破断运动及工作面来压规律进行了分析研究,结果表明:覆岩破断运动上,多层厚硬顶板较大的“垂向离层空间”和“自下而上”的顺次交替垮落孕育了顶板“高+低层位组合破断”的时空基础;“高低层位顶板组合破断”是“大周期”来压增强的关键诱因;同时,煤柱应力的时空演化受控于多层厚硬顶板的破断垮落。矿压显现上,工作面“大周期”立柱下缩量平均可达945 mm,持续距离12.10 m,并可由2~5次连续强来压组成;巷道煤柱应力集中系数达到1.80~2.30,影响范围为工作面前方126 m至后方471.3 m,具有明显的“高强度、大范围、长上升期”特点。针对该条件下的强矿压防治,分别提出了“弱化低位顶板、优化破断结构”和“弱化高位顶板、改变破断次序”的技术思路,并取得的了较好的应用效果。

分段多簇密切割压裂技术在淮南矿区煤层气抽采中的应用

针对淮南矿区碎软低渗煤层瓦斯抽采技术难题,以13-1煤层为例,在分析煤层及其顶底板概况的基础上,采用煤层顶板分段压裂水平井技术,充分利用水平井水平段,单段分3簇射孔,簇间距25 m,实现分段多簇密切割体积压裂改造。微地震监测结果表明,单段裂缝长度102.5~211.4 m,缝高17.3~27 m,裂缝主体向下延伸,实现了井筒与煤层的沟通。排水采气效果表明,最高产气量1519 m^(3)/d,取得了良好的产气效果。研究成果为淮南矿区煤层气地面预抽和瓦斯区域治理提供了工程借鉴。

煤巷断层区顶板破断机制分析及支护对策研究

煤矿开采过程中可能会发生各种事故,顶板事故是其中十分常见的一种,一旦发生事故,不仅会影响煤矿开采造成经济损失,而且可能会产生人员伤亡,危害巨大。在阐述断层区顶板出现事故的主要原因基础上,研究断层区顶板破断机制,最终总结了支护断层区煤巷顶板破断的合理措施,希望对相关工作人员以及煤矿行业发展都能够有所帮助。

掘进工作面冒顶防治技术研究

在煤矿工作面掘进过程中,冒顶对安全生产危险巨大,为此,需要对冒顶进行综合防治。首先分析了掘进工作面发生冒顶的原因,主要有靠近地质构造区域、空顶距过大、掘进速度过快和支护不合理等;然后分析了防治冒顶的技术,主要有加强地质探测、加强顶板支护、控制掘进速度和选择合适的掘进方式等。可以为煤矿的安全掘进提供一定的参考。

顶板疏水条件下矿压显现规律及防治对策

顶板疏水带来矿压显现,影响矿井安全生产。为降低顶板疏水对工作面回采的影响,在分析顶板疏水条件下矿压显现规律的基础上,提出了针对性的防治措施。防治措施主要包括:大直径钻孔卸压和加强巷道支护,通过改变煤岩变形系统控制量,提高矿压显现的临界应力;控制回采速度和顶板深孔预裂爆破,降低煤岩变形系统外部实际应力,降低矿压危险性。可以为顶板疏水引起的矿压显现防治提供一定的技术参考。

煤矿顶板风险动作原因及控制策略研究

中国属于世界范围内的煤矿大国,煤矿安全生产对于中国能源安全具有相当重要的现实意义,随着煤矿企业安全技术的不断提升,中国煤矿企业安全状况明显改善,但仍旧存在很多问题亟待解决,其中,煤矿顶板事故仍旧是困扰众多工作人员的问题。通过对相关文献进行查阅,从风险动作角度着手,对煤矿顶板事故的原因进行分析,并提出特定控制策略,以期提升相关单位对煤矿顶板安全事故的管理质量。

浅部中厚煤层切顶卸压沿空留巷技术研究与应用

为缓解矿井接续紧张局面,减少矿井井巷工程量,以鲁西煤矿3下A07工作面为研究背景,结合生产地质条件、理论分析及现场实测等方法,对浅部中厚煤层切顶卸压沿空留巷技术中关键参数展开研究,确定了预裂切顶高度为6.28~10 m,切顶角度为15°,爆破间距为600 mm,切缝装药结构为2+1+1。通过在巷道内布置测站点对留巷围岩变形量进行监测,并对切顶卸压沿空留巷效果进行评价。结果表明:巷道围岩变形量较小,顶板最大移近量为193 mm,两帮最大移近量为235 mm,采空区顶板岩石在垮落后充满矸石帮,具有良好稳定性,无明显底鼓现象,留巷完整且满足使用条件,研究结果可为类似条件下的切顶卸压沿空留巷工程提供参考。

龙岩市非煤矿山顶板事故分析与管理措施

顶板事故在非煤地下矿山事故中占比最多,顶板管理是非煤地下矿山安全管理的重点和难点。统计分析龙岩市2008—2023年共15a的顶板事故情况,总结非煤矿山顶板事故的特点。研究得出,矿井爆破工艺技术水平低及在大暴露空间下进行作业是顶板事故原因。提出改善措施,将中深孔爆破分段崩落采矿法代替空场法,但受到矿石价格影响,该方法成本高,当前可行性低;通过推广应用凿岩台车、撬毛台车等机械工具,严格控制井下采掘作业空间宽度和高度等措施,加强顶板管理,努力实现顶板零事故。

浅谈煤矿采煤工作面顶板控制措施

主要探讨了煤矿采煤工作面顶板控制措施。通过分析顶板控制对采煤工作面稳定性的影响、对确保采煤工作面安全和生产效率的重要性,以及顶板控制失效的情况,提出了一系列有效的顶板控制措施,包括选择支护方式、实施预防性支护和建立灾害监测预警系统。研究对煤矿采煤工作面的顶板控制具有重要的理论意义和实际应用价值。

采煤工作面顶板安全管理及事故预防

介绍了采煤工作面顶板分类,分析了采煤工作面顶板安全管理的现状,包括现有管理措施的效果和不足之处,以及事故发生的主要原因和问题挑战,探讨了采煤工作面顶板安全管理及事故预防措施,包括技术手段和管理措施。

厚煤顶动压影响巷道支护方案优化设计及应用

针对8206回风巷厚煤顶动压影响巷道存在的顶板易随采随冒的问题,综合运用现场调研、文献检索、理论分析等研究方法,分析该巷道原支护方案的缺陷及应该优化的方向,设计了一套“高预应力锚索整体支护方案”,并成功进行了工程实践。掘进支护后的矿压观测表明,实施优化后的支护方案后,巷道顶底板移近量、两帮移近量、顶板离层值均得到了有效控制,实现了安全高效掘进。