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.

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.

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.

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。

急倾斜煤层综合机械化采煤设备三机优化配套研究

常规的综采设备三机配套方法以开采效率优化为主,并未考虑三机生产能力配套问题,会影响三机运行性能。因此,设计急倾斜煤层综合机械化采煤设备三机优化配套方法。选择急倾斜煤层综采设备三机配套型式,根据煤层硬度、厚度、倾角等地质条件,选择合适的采煤机、液压支架、输送机等设备型式,确保三机结构尺寸配套。调整综合机械采煤设备三机配套参数,调整液压支架工作阻力、支护强度、采煤机截割速度、牵引速度等参数,使三机性能配套。匹配综采煤设备三机采支落煤输送生产能力,根据采煤机采煤能力小于输送机运输能力的原则,使三机生产能力配套。实例分析结果表明,该方法的优化配套效果更佳,能应用于实际生产。

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。

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。

急倾斜煤层顶板结构稳定性及其控制研究

为提高急倾斜煤层长壁放顶煤工作面围岩控制效果和支架稳定性,本文采用物理模拟和理论分析相结合的方法,对顶板结构和液压支架的稳定性进行了研究。结果表明:尾闸附近顶板下沉幅度大,切高小,主闸附近顶板下沉幅度相对较小;随着开采空间的增大,主闸门上方顶板岩层的冒落角增大。顶板岩层的垂直位移和水平位移特征表明,垮落块体在顶板结构的下铰点附近旋转,可能导致滑动失稳。煤层倾角大,使顶板结构更容易发生滑动失稳。在急倾斜煤层中,尾闸和主闸上方可以很容易地形成一个三铰拱。倾角的增长,沉降大门上方的拱脚形成显著减少,从而降低屋顶结构的概率变得不稳定由于大变形,而潜在的尾门上方的屋顶结构的滑动稳定性大大增加。

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。

急倾斜中厚煤层综采工艺优化

针对某煤矿的地质特点和急倾斜中厚煤层的分布情况,配套选型采煤设备,优化设计现有采煤工艺,并将优化设计后的采煤方案运用到矿井中进行试验生产。试验结果说明,优化的采煤方案提高了该煤矿的急倾斜中厚煤层开采效率以及安全性,提升了采煤生产量。

急倾斜特厚煤层走向长壁综放工作面顶煤运动规律研究

通过相似材料模拟试验及FLAC数值模拟,对宝积山煤矿急倾斜厚煤层走向长壁综放开采顶煤运移规律进行了研究。通过分析顶煤运移及主应力分布特点表明,不同角度下松散放出体仍为近似椭球体,在煤层倾斜方向上轴线并未偏移;工作面角度对放出体发育高度及形态有较大影响,同时影响高位顶煤放出。研究对704工作面放煤工艺的参数优化具有指导意义。

急倾斜煤层可采工艺性评价及应用研究

为了预测急倾斜煤层开采的效果和决策辅助技术,对急倾斜煤层可采工艺性进行综合评价.在急倾斜煤层开采工业性试验及开采实践的经验和统计数据分析的基础上,建立了适合急倾斜煤层地质条件开采工艺性块段评价的层次结构,影响急倾斜煤层开采的复合因素有8个,基元因素13个;运用多指标综合评价方法和模糊数学原理,构造了急倾斜煤层可采工艺性影响因素的评价函数,建立了模糊综合评价模型.用该模型对京煤集团大台煤矿289个工作面进行了评价计算,并且根据工作面块段的评价值对工作面单产进行了预测,结果表明,工作面中1级27个,占9.34%;2级87个,占30.1%;3级112个,占38.75%;4级63个,占21.8%。评价结果与开采结果基本相吻合.