Back-and-forth mining for hard and thick coal seams—research about the mining technology for fully mechanized caving working face of Datong Mine

The article introduced the key technology, mining process, and back-and-forth mining method for the caving working face of hard-thick coal seams in Datong mine, and researched this innovations process, optimized the systemic design and working face out-play, tried to perfect the caving mining technology of hard-thick coal seams further.

Theoretical description of drawing body shape in an inclined seam with longwall top coal caving mining

Understanding the characteristics of drawing body shape is essential for optimization of drawing parameters in longwall top coal caving mining.In this study,both physical experiments and theoretical analysis are employed to investigate these characteristics and derive a theoretical equation for the drawing body shape along the working face in an inclined seam.By analyzing the initial positions of drawn marked particles,the characteristics of the drawing body shape for different seam dip angles are obtained.It is shown that the drawing body of the top coal exhibits a shape-difference and volume-symmetry characteristic,on taking a vertical line through the center of support opening as the axis of symmetry,the shapes of the drawing body on the two sides of this axis are clearly different,but their volumes are equal.By establishing theoretical models of the drawing body in the initial drawing stage and the normal drawing stage,a theoretical equation for the drawing body in an inclined seam is proposed,which can accurately describe the characteristics of the drawing body shape.The shape characteristics and volume symmetry of the drawing body are further analyzed by comparing the results of theoretical calculations and numerical simulations.It is shown that one side of the drawing body is divided into two parts by an inflection point,with the lower part being a variation development area.This variation development area increases gradually with increasing seam dip angle,resulting in an asymmetry of the drawing body shape.However,the volume symmetry coefficient fluctuates around 1 for all values of the seam dip angle variation,and the volumes of the drawing body on the two sides are more or less equal as the variation development volume is more or less equal to the cut volume.Both theoretical calculations and numerical simulations confirm that the drawing body of the top coal exhibits the shape-difference and volume-symmetry characteristic.

Top coal caving mining technique in thick coal seam beneath the earth dam

It is important to study the mining technology under structures for raising the coal resources recovery ratio. Based on the geological and mining conditions, the top coal caving harmonic mining technique in thick coal seam beneath the earth dam was put forward and studied. The 5 factors such as the panel mining direction, panel size, panel location, panel mining sequence and panel advance velocity were taken into account in this technique. The dam movement and deformation were predicted after the thick coal seam mining and the effects of mining on the dam were studied. By setting up the surveying stations on the dam, the movement and deformation of the dam were observed during mining. By taking some protective measures on the dam, the top coal caving mining technique in thick coal seam beneath the earth dam was carried out successfully. The study demonstrates that harmonic mining in thick coal seam is feasible under the dam. The safety of the earth dam after mining was ensured and the coal resources recovery ratio was improved.

Fracture mechanics model of fully mechanized top coal caving of shallow coal seams and its application

Based on break characteristics of roofs in fully mechanized top-coal mining of thick shallow coal seams, a fracture mechanics model was built, and the criterion of crack propagation in the main roof was derived using the fracture mechanics theory. The relationships between the fracture length of the roof and the working resistance of the supports were discovered, and the correlations between the load on the overlying strata and the ratio of the crack's length to the thickness of the roof were obtained. Using a working face of Jindi Coal Mine, Xing county Shanxi province as an example, the relationships between the fracture length of the roof and the working resistance of the supports were analysed in detail. The results give a design basis in hydraulic top coal caving supports, which could provide useful references in the practical application. On-site experiment proves that the periodic weighting step interval of the caving face is 15–16 m, which is basically consistent with the theoretical analysis results, and indicates that the mechanized caving hydraulic support is capable of meeting the support requirements in the mining of a super-thick but shallowly buried coal seam.

Development and prospect on fully mechanized mining in Chinese coal mines

Fully mechanized mining(FMM)technology has been applied in Chinese coal mines for more than 40 years.At present,the output of a FMM face has reached 10-million tons with Chinese-made equipment.In this study,the new developments in FMM technology and equipment in Chinese coal mines during past decades are introduced.The automatic FMM technology for thin seams,complete sets of FMM technology with ultra large shear height of 7 m for thick seams,complete sets of fully mechanized top coal caving technology with large shear height for ultra-thick seams of 20 m,complete sets of FMM technology for complex and difficult seams,including steeply inclined seams,soft coal seams with large inclination angle,and the mechanized filling mining technology and equipment are presented.Some typical case studies are also introduced.Finally,the existing problems with the FMM technology are discussed,and prospect of FMM technology and equipment applied in Chinese coal mines is put forward.

宁正矿区新庄煤矿首采区侏罗系延安组8号煤层顶板涌(突)水危险性评价

针对新庄矿井水文地质条件特别是矿井水的涌(突)水水源和机理认识不清,直接影响新庄煤矿的安全、高效、绿色开采这一问题,通过水质分析和计算导水裂隙带发育高度,判定新庄矿井8号煤层顶板涌(突)水水源;同时在含水层的厚度、单位涌水量、物探含水层富水异常区、钻孔消耗量、岩芯采取率、地层脆塑性比6个主控因素的含水层富水性分析和综放开采条件下冒裂安全性分析基础上,通过多结果叠合对首采区8号煤层顶板涌(突)水危险性进行评价。结果表明:矿井顶板涌(突)水水源为下白垩统志丹群洛河组砂岩孔隙−裂隙含水层和中侏罗统直罗组、延安组上、中部(煤8层顶板以上)砂岩复合承压含水层,其中下白垩统志丹群洛河组砂岩孔隙−裂隙含水层是主要致灾水源。首采区内8号煤层导水裂隙带发育高度均能沟通洛河组砂岩含水层,首采区全区域为冒裂危险区。8号煤层顶板涌(突)水危险区中Ⅰ区主要分布在首采区的北部及中西部,Ⅱ区主要分布在首采区的中部及中西部,Ⅲ区主要分布在首采区的中东部及南部,Ⅳ区主要分布在首采区的东部及南部。

特厚煤层8.8 m超大采高综采面切眼放顶技术

上湾煤矿特厚煤层8.8 m超大采高12403综采面顶板不易自然垮落,在工作面初采阶段,易导致顶板初次垮落步距较大,在顶板大面积瞬间垮落时会产生强烈的强矿压和飓风现象,从而导致人员伤亡及设备损坏等。为了保证工作面初采阶段的安全生产工作,上湾煤矿通过引进井下定向长钻孔水力压裂工艺技术对切眼顶板进行预裂,同时配合切眼三角区强放技术,对特厚煤层8.8 m超大采高综采面切眼进行了初采放顶工作。实践表明:通过在上湾煤矿12403工作面进行煤层顶板定向长钻孔分段水力压裂工程施工,有效降低了顶板强度,缩小了初次放顶步距,为矿井安全高效回采提供技术保障,同时为大采高工作面初次放顶提供了治理经验。

提高8405综放工作面回采率途径探讨

为了解决厚煤层综放工作面开采过程中,顶煤冒放性差、回收率低等问题,通过分析北辛窑煤矿8405工作面放顶煤机理以及回采过程中煤炭损失原因,提出了8405工作面回采率提升的具体措施,并在现场应用,有效提高煤炭资源回收率。

6~10 m厚煤层超大采高液压支架及其工作面系统自适应智能耦合控制

厚煤层储量及产量占我国原煤总储量及产量的一半,通过梳理厚煤层开采历史沿革,总结了我国厚煤层开采40年来的技术及装备研发实践,系统分析了以高端大采高液压支架及围岩智能耦合理论为代表的6~10 m大采高综采高效智能化综采技术及装备研究进展,提出了大采高支护理论及围岩智能耦合控制的突破是厚煤层一次开采高度突破的首要因素,完善的感知体系建立是液压支架自适应支护的前提,数字技术的应用为大采高工作面高效推进及装备智能协同控制提供了新的技术途径;阐明了大采高综放液压支架与围岩耦合关系,剖析了采高增加对硬煤层冒放性的有利影响,提出了基于煤矸识别、放煤机构控制的“纯煤段记忆放煤+煤岩分界模糊段人工反馈式干预放煤”的智能放煤控制策略;分析了大采高开采“采–运”协同智能耦合控制关键技术,构建了基于采煤机牵引速度与刮板输送机链速间联动调节的工作面装备间多机异构耦合自适应协同控制模型;研发了厚煤层开采中10 m超大采高液压支架,分析了厚煤层开采不断突破开采高度极限的新认识,从开采装备、控制系统等方面提出厚煤层一次开采高度的突破的研发方向。

东欢坨矿8煤瓦斯异常的地质因素

运用压汞法和等温吸附法对开滦矿区东欢坨矿8煤储层特征进行研究,结合矿井实测瓦斯涌出量数据,分析了控制东欢坨矿8煤瓦斯异常涌出的地质因素。结果表明:瓦斯异常主控地质因素为地质构造及水文地质特征,东欢坨矿"水大瓦斯小,水小瓦斯大"的赋存规律明显。矿井瓦斯赋存形式主要为游离态,表现出在压性断层带时,瓦斯涌出量较小;在未导通煤系含水层情况下,张性断层带往往煤体破碎、孔裂隙相对发育,瓦斯涌出量显著增大,而在断层导通煤系含水层的水文异常区,瓦斯涌出量有明显减小的趋势。东欢坨矿瓦斯涌出量受多种因素的控制,筛选出煤层埋深、煤层厚度、煤层顶板含泥率和断层数作为主要控制因素,建立了具有较好相关性的瓦斯涌出量多变量数学预测模型;并通过灰色系统理论建模软件对瓦斯涌出量和各影响因子之间的关联度进行分析,得到断层数是瓦斯涌出量的最主要影响因素。

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。

汪家寨矿C409复杂难采厚煤层开采方法选择及建议

针对汪家寨矿C409复杂难采厚煤层合理开采方法选择进行了研究。首先,为进一步增加开采方法选择的直观性,就三种厚煤层开采方法一般适用条件及选择原则以表格形式进行了总结;其次,具体分析了C409复杂难采厚煤层开采需着重考虑的不利因素。在此基础上,进行了C409厚煤层开采方法选择对比分析和适应性综合评价。结果表明,在现有开采技术条件下,C409厚煤层采用放顶煤开采较合理,这与矿井目前实际采用的开采方法是一致的。最后,针对C409复杂难采厚煤层放顶煤开采可能遇到的问题,给出了具体建议,以指导其安全高效开采。

开采4～8m急倾斜煤层运输设备选型及布置方案探讨

开采4～8m急斜煤层,采用F3200/17.5/27F型放顶煤液压支架。根据工作面开采方法,依据支架宽度、煤层厚度、支架数量以及顺槽输送机安放位置,对扩巷工作面及放顶煤工作面上输送机选型及布置方案进行了探讨。

ZZF5200/19/32S型坚硬特厚煤层放顶煤液压支架的研制

该支架是针对靖远矿务局红会一矿坚硬、特厚煤层综放开采技术的需要研制而成的。试用结果表明,支架的结构合理,支护性能良好,与其它设备配套性能良好。

近距煤层合层综放工作面矿压显现规律研究

针对近距煤层合层综放开采覆岩移动破坏与矿压显现规律等问题,以涡北煤矿842首采综放工作面为工程背景,采用相似模拟试验和数值分析手段对工作面开采过程进行研究。结果表明:相似模拟试验下覆岩冒落带高度为38 m,开切眼附近裂隙带的高度为103.8 m,停采线附近裂隙带的高度为95.4 m,基本顶初次来压步距为28 m,周期来压步距为17.5 m。由数值分析得到采场围岩位移场与应力场的变化颇为相似,分析采场前方支承压力分布特征与相似模拟试验的结果相吻合。研究结果可为近距煤层合层综放工作面煤柱宽度、工作面支护参数设计提供技术指导。

煤岩物性及地质因素对嘉乐泉煤矿8号煤层瓦斯的耦合控制

瓦斯突出是影响矿井安全生产的主要灾害之一,厘清其赋存规律是矿井开采的必要条件。为厘清西山煤田嘉乐泉煤矿8号煤层瓦斯地质特征及赋存规律,基于研究区钻孔录井信息绘制了瓦斯含量等值线图,并探讨了地质因素和煤岩物性对瓦斯含量的影响。结果表明:8号煤层瓦斯含量整体偏低,为低瓦斯矿井,其含量南北向呈带状分布,东西向集中连片分布,整体呈现北低南高特征;断裂不发育的宽缓单斜利于瓦斯富集;煤层埋深、上覆盖层厚度和顶底板封闭性顶底板岩性控制瓦斯含量的关键;岩溶陷落柱也为瓦斯提供了重要的富集空间。此外,煤层厚度和煤岩物性对8号煤层瓦斯含量也有一定影响,但体现的相关性较弱。研究结果对嘉乐泉煤矿8号煤层瓦斯防治工作有一定的参考意义。

郭二庄9#煤带压开采底板突水灰色风险评价

针对郭二庄井田下组9#煤带压开采中存在的底板突水风险影响因素的不确定性,采用灰色风险计算模型和方法,结合井田已有突水、出水点水位标高、矿井最大涌水量及单位涌水量等相关信息统计,构建灰色风险计算模型,对井田受采动影响后煤层底板发生突水风险的概率和风险性变异进行评价。计算结果表明郭二庄井田下组9#煤带压开采存在底板突水风险性大,煤层开采前应慎重作出避让和分区隔离开采、探治结合等有效的补救措施,减少突发水害事故的发生。

巨厚煤层综放工作面雨季过季节性河流实践与研究

柴沟煤矿是年产8 Mt的高产高效矿井,计划回采的1503工作面埋深200~255 m,采厚超过12 m,是典型的薄基岩巨厚煤层开采工作面,采动形成的导水裂隙带发育至地表。该工作面在雨季需穿越1条季节性河流——小南沟河,为防止洪水沿导水裂隙灌入井下,造成安全事故,通过分析工作面地表地形及水文地质情况,确定采取“岩移观测指导预填,工作面上游筑坝拦截+泄水孔分流”的综合防治水方案。该方案的实施顺利实现了季节性河流下巨厚煤层综放工作面的安全回采。

厚松散层下高强度综放开采地表沉陷规律研究

在陕北地区浅埋厚煤层、厚松散层地质条件下,以某大型煤矿大采高综采工作面采动地表沉降监测数据为基础,选取沿工作面走向、倾向两条观测线为研究对象,分析研究各观测点全周期下沉变化及对应时空关系,采用数理统计、公式计算、数据拟合等方法确定地表移动动态变化相关参数,探讨采动工作面的地表沉降特征和变化规律。结果显示:工作面采动初期上覆岩层的运动范围已波及到地表,随着工作面不断推进,其地面影响范围一直在超前;当工作面回采完成时,下沉量迅速衰减,逐步趋于稳定。走向线最大下沉值3 715 mm,倾向线最大下沉值3 327 mm,工作面推进在400~600 m,下沉速度超过200 mm/d,最大可达268 mm/d。地表沉降系数0.58,起动距102.6 m,超前影响角54.9°,最大下沉速度滞后角71.8°。地表移动持续时间282 d,起动阶段时间短,仅为18 d,活跃阶段移动速度大、变形剧烈,衰退阶段持续时间较长达199 d,反映了浅埋厚松散层综放高强度开采条件下,地表移动发展快、稳定也快的特征。