Comprehensive analysis of safe mining to heavy and steep coal seam under complex geophysics environment

In virtue of effect of N-S intensive ground stress and mining disturbance to +579E2EB_(1+2) mining site at Weihuliang Mine,the dip angle and section height is 65° and 52 m,respectively,the collapses happed frequently during mining.Firstly,mining condi- tions,spatial structure and parameters were investigated.Then physical simulation and dynamic numerical tracing and elaborate simulation relating roof and top-coal were ap- plied based on 2D-Block Program and quantitative regularity of stress at variable depths had been estimated.Furthermore,it was manifested that effective measures,i.e.,fast mining,control symmetrical top-coal-caving at dip and strike directions,optimizing ventila- tion system,active-stereo preventing gas were performed successfully in mining practice. Ultimately,the derived dynamic hazard were prevented so as to safety mining.

Subsidence control method by inversely-inclined slicing and upward mining for ultra-thick steep seams

Ultra-thick steep coal seam mining will inevitably lead to the increase of greater and violent ground subsidence and deformation.A subsidence control method by inversely-inclined slicing and upward mining is proposed in this paper.By this method,the sequence of collapse of overlying strata and the direction of propagation of strata movement are changed,the extent of roof-side deformation thereby is lessened,and boundary angle of roof-side subsidence is reduced by 5°-10°.The mechanism of this mining method for control of strata movement has been evidenced by numerical simulation and experiments with similarity materials.A subsidence prediction model based on the variation of mining influence propagation angle can be used to evaluate the surface movement and deformation of the mining method.The application of the method in No.3 Mine in Yaojie mining area has yielded the expected result.

Research on drawing coal effects in the dipping and steep——dipping coal seams

Controllable drawing roof coal mining method is applied either to rently inclined seam or to big dipping seam. This paper sums up four corresponding methods according to conditions of our country, and analyses the coal-recovering effects and proves applicated conditions and measures for improving by "drawing coal theory of the ellipsoid". Its conclusion basically consists with practice. This work is of guiding meaning for designing drawing coal technology.

Comparative study of mining methods for reserves beneath end slope in flat surface mines with ultra-thick coal seams

The paper aims to identify a reasonable method for mining ultra-thick coal seams in an end-slope in surface mine, With a case study of Heidaigou surface coal mine(HSCM), the paper conducted a comparative research on three mining methods, namely Underground Mining Method(UMM), Highwall Mining System(HMS) and Local Steep Slope Mining Method(LSSMM). A model was firstly established to simulate the impact that UMM and HMS exert on monitoring points and surface deformation. The way that stripping and excavation amount varies with different slope angle, and the corresponding end slope stability were analyzed in the mode of LSSMM. Then a TOPSIS model was established by taking into account six indicators such as recovery ratio, technical complexity and adaptability, the impact on surface mining production, production safety and economic benefits. Finally, LSSMM was determined as the best mining method for mining ultra-thick coal seams in end slope in HSCM.

Feasibility analysis of gob-side entry retaining on a working face in a steep coal seam

Based on the decline in exploitation of coal resources, steep coal seam mining and mining face tensions continue to explore the feasibility analysis of steeply inclined faces in the gob. One of the key factors in utilizing the technology of gob-side entry retaining in steep coal seams is to safely and effectively prevent caving rock blocks from rushing into the gob-side entry by sliding downwards along levels. Using theoretical analysis and field methods, we numerically simulated the mining process on a fully-mechanized face in a steep coal seam. The stress and deformation process of roof strata has been analyzed, and the difficulty of utilizing the technology is considered and combined with practice in a steep working face in Lvshuidong mine. The feasibility of utilizing the technology of gob-side entry retaining in a steep coal seam has been recognised. We propose that roadways along the left lane offshoot body use a speciallymade reinforced steel dense net to build a dense rock face at the lower head. The results show that the lane offshoot branch creates effective roof control, safe conditions for roadway construction workers, and practical application of steeply inclined gob.

Numerical simulation analysis of covering rock strata as mining steep-inclined coal seam under fault movement

The fault is one important factor for the stability of overburden strata caused by steeply inclined coal seam. The stress and displacement change of overburden strata caused by steeply-inclined coal seam mining activity under faulting was simulated by FLAC2D finite differential program on the basis of Zhaogezhuang mining example belonging to Kailuan Mining Group. From the results, the stress and displacement clouding image after mining became complex because of the fault, that is, a kind of weak structural plane. The stress concentration region concentrated around the goaf, and also around the fault plane. As the mining depth increases, the stress and displacement within the fault zone change significantly. This movement and deformation characteristic of overburden strata can provide theoretical basis for the similar mining condition.

Hydraulic support stability control of fully mechanized top coal caving face with steep coal seams based on instable critical angle

Analyzed the support instable mode of sliding,tripping,and so on,and believed the key point of the support stability control of fully mechanized coal caving face with steep coal seams was to maintain that the seam true angle was less than the hydraulic support instability critical angle.Through the layout of oblique face,the improvement of support setting load,the control of mining height and nonskid platform,the group support system of end face,the advance optimization of conveyor and support,and the other control tech- nical measures,the true angle of the seam is reduced and the instable critical angle of the support is increased,the hydraulic support stability of fully mechanized coal caving face with steep coal seams is effectively controlled.

Study on fasART neuro-fuzzy networks for distinguishing the difficulty degree of top coal caving in steep seam

Distinguishing the difficulty degree of top coal caving was a precondition of the popularization and application of the roadway sub-level caving in steep seam. Because of complexity and uncertainty of the coal seam, the expression of influence factors was diffi-culty with exact data. According to the fuzzy and uncertainty of influence factors, triangular fuzzy membership functions were adopted to carry out the factors ambiguity, of which the factors not only have the consistency of semantic meaning, but also dissolve sufficiently expert knowledge. Based on the properties and structures of fasART fuzzy neural net-works of fuzzy logic system and practical needs, a simplified fasART model was put for-ward, stability and reliability of the network were improved, the deficiency of learning sam-ples and uncertainty of the factors were better treated. The method is of effective and practical value was identified by experiments.

急倾斜巨厚煤层复杂空间结构区微震时空演化规律及诱冲机理

煤矿冲击地压灾害的发生与空间结构密切相关,尤其在复杂空间结构区灾害发生更频繁。掌握煤层开采复杂空间结构区煤岩灾变规律并揭示其发生机制对于冲击地压防控具有重要意义。以乌东煤矿为研究背景,采用数值模拟、微震监测、理论分析等方法,研究了岩柱应力异常尺寸效应,分析了复杂空间结构区微震时空演化规律,揭示了复杂空间结构下冲击地压发生机理,评估了煤层开采不同区域的冲击危险性。研究结果表明:①急倾斜岩柱厚度更窄、出露高度更大其撬动效应更强,岩厚变异应力异常形成5个分区。②岩柱厚度更窄区域微震频次更多,能量更高,时空活动度更强,离散性更高。高应力区、应力梯度区、应力平稳区依次呈现“低频次-高能量”、“高频次-高能量”、“低频次-低能量”的微震响应特征。③特殊空间结构区域微震事件簇集且能级增大,时空活动度及离散性陡增,尤其在结构边缘该特征更明显,能量积聚及释放速率增大,冲击地压发生的概率及强度更高。位于岩柱更窄区域的特殊空间结构内微震活动更剧烈。④岩柱厚度越窄(煤柱高度越大)则岩柱向深的弯矩及能量增长速率越快,冲击危险性更高。依据结构面强度效应推断出断裂带发生滑移错动,是能量积聚与释放的优势区域。揭示冲击地压发生机理为高静载及低临界载荷共同作用,基于应力集中特征评估煤层开采不同区域的冲击危险性。

急倾斜煤层巷道冒落带注浆加固技术的研究与应用

急倾斜煤层巷道掘进过程中,经常受到高地应力和断层构造带的影响,易造成煤层顶板冒落,影响巷道的掘进和煤矿的安全生产。针对上述问题,以石洞沟煤矿31114运输巷为工程背景,采用KWJG-4无机双组分化学材料对冒落带破碎煤岩体进行注浆加固,将破碎围岩黏结为具有一定强度的密实体,从而有效加固冒顶区的破碎围岩,提高顶板的整体强度及完整性,改善工作面顶板的受力状况,实现掘进巷道安全、快速、高效过冒落带。对于煤矿生产过程中遇到类似巷道冒落破碎带问题,该方法具有一定的借鉴和指导意义。

急倾斜中厚煤层单一巷道放顶煤采煤方法研究与应用

为解决某矿急倾斜中厚煤层倾角及厚度变化大的开采问题,提出了“急倾斜中厚煤层单一巷道放顶煤采煤方法”。该采煤方法是沿急倾斜煤层倾斜方向划分为若干区段,每个区段沿急倾斜煤层走向仅布置1条巷道。此巷道服务于1个采煤区段,担负工作面通风、运输和行人等任务。对单一巷道放顶煤采煤方法的巷道布置、综放工艺和沿空留巷方法进行了探讨。实践表明,该采煤方法使采煤工作面形成全负压通风,避免了巷道与采空区窜风,杜绝了采空区瓦斯积聚和遗煤自燃,实现了采煤机械化,提高了急倾斜中厚煤层的开采效率和煤炭回收率。单一巷道放顶煤采煤法为类似急倾斜煤层安全、高效开采提供了技术支撑。

基于钻孔瓦斯涌出规律的突出危险性预测模型

为提高急倾斜煤层上山掘进过程中煤与瓦斯突出危险性预测的准确性,首先,基于Mohr-Coulomb准则建立钻孔瓦斯流动模型;其次,通过数值模拟定量分析钻孔瓦斯初始涌出量和瓦斯压力之间的关系;最后,使用ZTL20/1000-Z型矿用隔爆预测装置对贵州洪兴煤矿111707上山掘进面进行现场试验。结果表明:钻孔初始瓦斯涌出量与瓦斯压力呈正相关关系,其相关系数为0.977 3,钻孔初始瓦斯涌出量可以作为预测煤与瓦斯突出的一项参考指标;随着钻孔深度的增加,钻孔初始瓦斯流量会经历“稳定—增加—降低—稳定”4个阶段,钻孔瓦斯流量峰面积可以反映煤与瓦斯突出危险性。

下伏煤层对既有重载铁路隧道安全性的影响

为研究重载列车振动荷载作用下隧底下伏煤层对隧道的影响,结合现场监测结果梳理隧道病害类型及原因,通过数值模拟分析隧底结构与下伏煤层的动力响应,提出病害处治措施。结果表明:隧底病害主要为基底围岩不密实、空洞引起的不均匀沉降;产生病害的原因为列车振动荷载作用下节理裂隙发育的软弱煤层承载力降低;仰拱中心最小安全系数不满足规范要求,在煤层应力状态持续恶化的情况下结构可能发生破坏。结合工程经验,采取打设锁脚锚管、基底注浆处治措施,效果良好。

急倾斜巨厚煤层矿震诱冲机制及时-空特征

针对急倾斜巨厚煤层赋存环境复杂,开采过程矿震频发,冲击危险性高的问题,通过构建岩柱力学模型及数值模型、统计分析现场矿震事件,掌握急倾斜巨厚煤层开采的煤岩灾变规律,形成基于动静载理论的急倾斜巨厚煤层矿震诱冲机制。选取5个微震指标深入分析矿震发生的异常前兆及时间跨度特征,预警冲击危险并把握补强卸压时机;通过微震事件定位掌握矿震发生的空间特征,明确卸压关键区域,基于矿震发生的时空特征提出防冲策略。研究结果表明:急倾斜巨厚煤层岩柱在直立极限长度范围内其弯曲变形效应随采深增大愈加明显,岩柱内部能量积聚随采深增加也愈高,岩柱及煤层内高能量积聚区域受开采扰动发生大尺度破裂产生矿震,形成动载震动波,动静载叠加易诱发冲击;矿震发生前日总能量-频次、A(b)、S均出现低值异常,b、P(b)均出现高值异常,异常跨度即表示矿震孕育过程。矿震发生时日总能量-频次、A(b)、S均快速跃升至高值,b值、P(b)值均快速降低至低值;矿震事件发生前在空间上某区域出现明显的缺震现象,缺震程度越高矿震能量越大,据此可对缺震区域采取补强卸压措施,从源头降低冲击危险性。防冲策略包括对岩柱及煤层充分卸压,弱化冲击源头及路径,加强采场与巷道支护,使其具有一定的抗冲能力。但不能保障开采时没有冲击危险,因此需对开采过程煤岩活动密切监测,识别高能矿震发生的时空异常前兆,以便及时精准的采取补强卸压及支护、撤人等安全防护措施。

急倾斜煤层分段开采下部煤岩体应力及位移演化规律

为了掌握急倾斜特厚煤层分段开采时工作面下部煤岩体应力及位移演化规律,采用数值模拟方法研究了工作面下部煤岩体和工作面底板的应力及位移分布,并分析了分段高度和开采深度对下部煤岩体应力及位移的影响。研究表明:上分段开采后,下部不同深度煤岩体卸压范围均呈长轴沿煤层走向的椭圆状,但卸压范围并不对称,底板侧和顶板侧的煤岩体卸压程度不同,靠近底板侧卸压程度更大。下部煤体卸压深度大小为底板侧>工作面中部>顶板侧。煤层底板不同深度出现不对称卸压区,靠近回采分段上端部的煤层底板处垂直应力明显集中。急倾斜煤层分段开采,段高对下部煤体的卸压深度范围影响较小。开采深度不同时,随着埋深增加,工作面下部煤岩体应力集中区域增大,下部同一深度煤体的垂直应力、垂直位移均出现明显增加,开采深度对工作面下部煤岩体的卸压范围影响明显,埋深越大卸压范围也越大。

标准指导下的金家渠煤矿大倾角煤层智能化工作面建设

以煤矿智能化建设指南和综采工作面安装回收工作标准为指导,介绍了智能化工作面设备配套原则及其配置标准;针对工作面的空间尺寸规格和形状决定智能化工作面设备的安装质量和作用效果发挥,研究确定了两巷相关参数以及开切眼施工工艺;阐述了金家渠煤矿大倾角煤层110401智能化工作面采煤机、液压支架、刮板输送机、转载机、破碎机等设备以及电缆管道的安装布置工艺;依据工程设计标准,对该工作面进行了安装施工预验收,并参照山西省地方标准DB14/T 20602020智能煤矿建设规范,对该智能综采工作面进行了整体验收。

急倾斜特厚煤层开采保护层保护范围及效果研究

针对窑街煤电集团三矿急倾斜特厚、煤(岩)与CO_(2)突出煤层,经过多年的开采治理摸索、实践、调整、总结,形成了三矿煤与CO_(2)特有的治理模式。急倾斜特厚煤层上分层工作面回采后对下分层工作面进行有效卸压保护,进回风巷施工卸压爆破孔,进一步增大了被保护层的有效保护范围,提升了保护效果。通过开采保护层技术研究及应用,有效降低工作面的突出危险,取得了较好的技术经济效益。

新疆天池能源南露天矿南端帮边坡参数优化

为了提升煤炭资源回收利用率,以新疆天池能源南露天煤矿南端帮为研究背景,通过分析该露天煤矿边坡工程技术参数,对提升煤炭资源回收利用率进行了研究;通过采用极限平衡法和强度折减法分别对南露天矿南端帮不同时期的二维剖面模型进行稳定性分析。结果表明:2022—2023年边坡稳定系数较低,基于边坡稳定性计算结果,通过调整南端帮边坡设计参数,边坡稳定系数提升明显。