Key technologies and equipment for a fully mechanized top-coal caving operation with a large mining height at ultra-thick coal seams

Thick and ultra-thick coal seams are main coal seams for high production rate and high efficiency in Chinese coal mines, which accounts for 44 % of the total minable coal reserve. A fully mechanized top-coal caving mining method is a main underground coal extraction method for ultra-thick coal seams. The coal extraction technologies for coal seams less than 14 m thick were extensively used in China. However, for coal seams with thickness greater than 14 m, there have been no reported cases in the world for underground mechanical extraction with safe performance, high efficiency and high coal recovery ratio. To deal with this case, China Coal Technology ＆ Engineering Group, Datong Coal Mine Group, and other 15 organizations in China launched a fundamental and big project to develop coal mining technologies and equipment for coal seams with thicknesses greater than 14 m. After the completion of the project, a coal extraction method was developed for top-coal caving with a large mining height, as well as a ground control theory for ultra-thick coal seams. In addition, the mining technology for top-coal caving with a large mining height, the ground support technology for roadway in coal seams with a large cross-section, and the prevention and control technology for gas and fire hazards were developed and applied. Furthermore, a hydraulic support with a mining height of 5.2 m, a shearer with high reliability, and auxiliary equipment were developed and manufactured. Practical implication on the technologies and equipment developed was successfully completed at the No. 8105 coal face in the Tashan coal mine, Datong, China. The major achievements of the project are summarized as follows： 1. A top-coal caving method for ultra-thick coal seams is proposed with a cutting height of 5 m and a top-coal caving height of 15 m. A structural mechanical model of overlying strata called cantilever beam-articulated rock beam is established. Based on the model, the load resistance of the hydraulic support with a large mining height for top-coal caving method is determined. With the analysis, the movement characteristics of the top coal and above strata are evaluated during top-coal caving operation at the coal face with a large mining height. Furthermore, there is successful development of comprehensive technologies for preventing and controlling spalling of the coal wall, and the top-coal caving technology with high efficiency and high recovery at the top-coal caving face with a large mining height. This means that the technologies developed have overcome the difficulties in strata control, top-coal caving with high efficiency and high coal recovery, and enabled to achieve a production rate of more than 10 Mtpa at a single top-coal caving face with a large mining height in ultra-thick coal seams; 2. A hydraulic support with 5.2 m supporting height and anti-rockburst capacity, a shearer with high reliability, a scraper conveyor with a large power at the back of face, and a large load and long distance headgate belt conveyor have been successfully developed for a top-coal caving face with large mining height. The study has developed the key technologies for improving the reliability of equipment at the coal face and has overcome the challenges in equipping the top-coal caving face with a large mining height in ultra-thick coal seams; 3. The deformation characteristics of a large cross-section roadway in ultra-thick coal seams are discovered. Based on the findings above, a series of bolt materials with a high yielding strength of 500-830 MPa and a high extension ratio, and cable bolt material with a 1 × 19 structure, large tonnage and high extension ratio are developed. In addition, in order to achieve a safe roadway and a fast face advance, installation equipment for high pre-tension bolt is developed to solve the problems with the support of roadway in coal seams for top-coal caving operation with a large mining height; 4. The characteristics of gas distribution and uneven emission at top-coal caving face with large mining height in ultra-thick coal seams are evaluated. With the application of the technologies of gas drainage in the roof, the difficulties in gas control for high intensive top-coal caving mining operations, known as ＂low gas content, high gas emission＂, are solved. In addition, large flow-rate underground mobile equipment for making nitrogen are developed to solve the problems with fire prevention and safe mining at a top-coal caving face with large mining height and production rate of more than 10 Mtpa. A case study to apply the developed technologies has been conducted at the No. 8105 face, the Tashan coal mine in Datong, China. The case study demonstrates that the three units of equipment, i.e., the support, shearer and scraper conveyor, are rationally equipped. Average equipment usage at the coal face is 92.1%. The coal recovery ratio at the coal face is up to 88.9 %. In 2011, the coal production at the No. 8105 face reached 10.849 Mtpa, exceeding the target of 10 Mtpa for a topcoal caving operation with large mining height performed by Chinese-made mining equipment. The technologies and equipment developed provide a way for extracting ultra-thick coal seams. Currently, the technologies and equipment are used in 13 mining areas in China including Datong, Pingshuo, Shendong and Xinjiang. With the exploitation of coal resources in Western China, there is great potential for the application of the technologies and equipment developed.

Mechanism and practice of rock control in deep large span cut holes

Deep large span cut holes are difficult to stabilize. The 7801 cut hole in the Lu'an Wuyang Mine was used as this project's background. The main factors affecting large span cut hole stability are analyzed. Pre- stressed bolting theory was used to design a roof control method for a large span roadway. By reducing the span and applying equal strength coordinated supports the rock could be stabilized. The control prin- ciples and methods are given herein along with the analysis. A double micro arch cross section roadway is defined and its use in solving the current problem is described. Beam arch theory was used to build a model of the double micro arch cross section roadway. A support reverse force model for the arch foot intersection was also derived. A support method based upon reducing the width of the large span in the cut hole is presented. These results show that the reduced span of the roadway roof plus the use of cable anchors and single supports gives an effective way to control the large span cut hole. On site monitoring showed that the reduced span support from the double micro arch cross section roadway design had a significant effect. The roadway surface displacement was small and harmful deformation of the cut hole was effectively controlled. This will ensure its long term stability.

面间煤柱与顺槽“掘-充-留”一体化科学问题与技术

我国将煤炭作为兜底保障能源的局面短期内无法改变,仍将长时间面临煤炭资源保护与煤基固废利用率低的难题。通过创新采掘方法,同时实现提高煤炭资源回采率、规模化处置煤基固废,为煤炭行业绿色可持续发展提供了新途径。在深入调研煤炭资源开采技术发展现状的基础上,提出了煤矿“掘-充-留”掘进新工法。从大断面巷道快速掘进、连续高效充填和巷道安全留设3个方面,通过理论分析、数值模拟等手段,系统论述了“掘-充-留”工法的科学问题和关键技术,研究结果表明:①针对大断面巷道快速掘进、掘进工作面围岩稳定性控制等工程难题,凝练了煤岩特性与掘进机截割参数匹配机制、覆岩载荷空间传递机制与围岩变形机理、锚杆/索-顶板相互作用关系及支护机制3个科学难题,构建了以掘进区地质环境超前实时感知、落-装-运煤多工序智能协同作业、钻锚支架随掘随支围岩时效控制和大断面巷道防漏风及通风优化为核心的技术体系;②从大断面巷道承载体系及时构建及其承载性能调控两个方面凝练了连续高效充填的科学问题,包括充填体-煤层-锚杆/索协同承载机制、多元固废基充填材料水化固结机制,明晰充填体物理力学特性时空演化规律,建立了充填空间安全高效搭建、充填材料工作性能调控、充填材料流动-固结感知为核心的连续高效充填关键技术体系,相关理论与技术的突破可以为充填材料的原材料优选及配比设计、添加剂开发/选型及工作性能调控、掘进速率及充填步距优化设计、充填体固结监测等提供基础理论依据;③基于巷道安全留设及全生命周期内围岩易断裂、易片帮和易损伤等关键难题,阐述了巷道围岩应力场时空分布特征、巷道变形与损伤演化机制、巷道围岩工程质量监测与稳定性调控理论3个科学问题,形成了以巷道围岩稳定性智能预警、巷道围岩变形控制为核心的关键技术体系。开展煤矿“掘-充-留”工法的科学研究与工程示范,实现固废规模化处置-面间煤柱高效回收-顺槽快速掘进的协同,可以推动煤炭行业绿色低碳转型发展。

区段煤柱下大断面回采巷道不同成巷方式分析研究

为了探究在区段煤柱下大断面巷道在掘进时受到扰动最小的一种成巷方式,以乌兰色太煤矿掘进52202工作面运输顺槽为研究背景,针对该工作面实际地质资料,通过数值模拟分析了大断面巷道在不同成巷方式条件下的塑性区形态、应力场及位移场分布规律。结果表明,先掘进5.4 m宽正常巷道,后扩帮2 m的成巷方式为最优成巷方式,将其应用于工程实践,为同类型区段煤柱下大断面巷道提供参考依据。

矿井采煤过程中大断面巷道支护技术研究

煤炭资源是中国重要的能源资源之一,然而在矿井采煤过程中,巨大煤矿的开采和应力变化等因素导致支护不足和大断面巷道变形严重。为了解决这一问题,需要开展更深入、更系统的研究。首先介绍了大断面巷道的特点以及在采煤过程中存在的支护难题,包括巷道变形、支架开裂等问题。然后分析了传统支护方式存在的不足之处,并提出了一种新型支护技术——填充式支护技术。该技术采用填充材料将巷道周围空隙填满,从而增强了支护效果,提高了大断面巷道开采的安全性和可靠性。

深部特厚煤层综放沿空掘巷煤柱优化及巷道支护

为研究深部大采高综放工作面窄煤柱沿空掘巷巷道矿压控制问题,以国能宁煤集团枣泉煤矿2^(-2)特厚煤层130203大采高综放工作面回风巷道为背景,基于实用矿山压力理论,建立了巷道围岩内、外应力场动态结构力学模型,运用理论计算和数值计算针对不同尺寸煤柱煤体应力对比分析,将原留设15 m护巷煤柱缩小至5 m进行了煤柱优化。结果表明:在稳定的内应力场掘巷有利于巷道的稳定性,避免了顶板事故及冲击地压相关灾害的发生,现场5 m小煤柱护巷工程应用中,130203回风巷道小煤柱侧变形量为1050 mm,实体煤帮变形量为400 mm,两帮呈现不对称性变形,底板局部底鼓量为1400 mm;深部特厚煤层综放开采沿空掘巷采用5 m小煤柱护巷方案设计正确,极大改善了巷道围岩的应力环境,整体设计满足生产要求,现场应用良好。130203工作面小煤柱沿空掘巷技术成功应用,为矿井开采提供了可靠的科学依据。

大断面半煤岩巷道变形破坏机理研究及控制技术

针对大断面半煤岩巷道围岩变形控制难题,以小保当煤矿一号井大断面半煤岩巷道为研究背景,测试了巷道围岩岩层分布、围岩地应力分布及裂隙发育,分析了巷道围岩的变形破坏演化特征。通过实验室试验以及数值模拟分析了半煤岩组合体力学性能及其变形破坏形态,揭示了强度较低的煤体最先在煤岩交界面发生破裂、滑移,变形不断向深部延伸,随着煤岩体完整性及强度的持续弱化,造成巷帮由下而上的非均匀渐进性失稳破坏,揭示了提高大断面半煤岩巷道围岩稳定性的关键在于控制煤岩交界面非协调变形。基于此提出了采用高预应力锚杆支护与薄弱区域加强支护的变形控制思路,制定了小保当一号井大断面巷道半煤岩巷道围岩变形控制方案,并开展了井下工业试验,取得了较好的应用效果,在监测期内巷道顶板的位移量为28 mm,两帮的位移量为80 mm,底板的位移量为43 mm,随后围岩变形趋于稳定,巷帮煤岩交界处的变形控制效果显著,表明采用该方案可有效控制大断面半煤岩巷围岩变形。

厚煤层大断面沿空巷道变形破坏机理及控制技术

针对沿空巷道受多次采动叠加影响极易发生变形失稳破坏的难题,以某矿1505W工作面厚煤层综放开采工作面为研究背景,综合采用理论分析、现场实测、数值模拟等多种研究方法探讨分析了沿空巷道围岩失稳破坏机制,并提出了围岩“浅部、深部、表层”控制方案。现场试验结果表明,提出的控制方案能够使巷道浅、深部围岩形成统一的整体,有效抑制了沿空巷道围岩变形,提高了巷道的稳定性。

破碎软煤大变形回采巷道稳定性分析及支护技术研究

鸿兴煤业由于巷道煤层软弱、裂隙发育、围岩破裂变形不致密、支护参数不合理等问题,给矿井的安全开采带来了巨大的挑战。结合理论,分析了主动支护和被动支护对巷道稳定性的影响,提出了新的支护方案,并进行了现场试验。试验过程中,在29107巷道中实施了“螺栓、W钢带”+“锚索、锚索梁”+“工字钢棚”的主动式被动耦合支护方案,并对巷道两壁和顶板、底板位移收敛变形进行了实时监测,结果表明,该方案有效地控制了巷道围岩变形,保证了巷道的稳定性。

高瓦斯大断面煤巷智能快掘条件下围岩控制研究

针对高河煤矿高瓦斯大断面煤巷智能快掘条件下的围岩控制问题,根据悬吊理论、普氏理论对E2312进风顺槽锚杆、锚索支护参数进行理论计算,初步确定了部分参数,采用数值模拟方法对智能快掘巷道围岩控制效果进行模拟分析,揭示锚杆、锚索协同锚固效应及其双层锚固平衡拱结构形成机理,并确定快掘条件下的最终支护参数。通过对不同支护参数和掘进速度分别制定了多组数值模拟方案,对比分析巷道围岩锚固效应、塑性区发育范围以及顶板下沉量和两帮移近量变化曲线,结合现场工程应用综合分析得出,在一定范围内提高掘进速度的同时,结合对支护参数的优化,更加有利于巷道的围岩稳定控制。

瑶渠煤矿大巷间煤柱尺寸确定及支护优化

为研究大巷过剥蚀区时大巷间煤柱合理尺寸及围岩稳定性,以瑶渠煤矿西采区Ⅱ回风大巷为研究对象,采用理论分析、数值模拟等研究方法,建立了煤柱尺寸计算模型,揭示了煤柱在8 m、10 m、12 m、14 m条件下巷道围岩应力、位移及塑性区的分布规律,确定了过剥蚀区大巷间煤柱的合理尺寸,并优化了西采区Ⅱ回风大巷的支护参数。研究结果表明,瑶渠煤矿西采区Ⅱ回风大巷与辅运大巷之间煤柱尺寸由14 m减小至8 m时,巷道围岩内的垂直应力由1.381 MPa增加至1.465 MPa、最大位移量增加了12.52%,塑性区逐渐贯通煤柱。当煤柱尺寸为10 m时,煤柱塑性区处于贯通的临界区域,煤柱内部具有一定的弹性核区域,且煤柱尺寸大于理论计算的9.23 m,能够满足巷道围岩的稳定性。综合考虑,确定煤柱最小合理尺寸为10 m。对10 m煤柱尺寸下西采区Ⅱ回风大巷进行支护优化,采用帮部3根锚杆支护后巷道围岩应力、位移和塑性区均显著改善,保证了巷道围岩的稳定性。

南阳煤业大断面巷道支护方案设计及应用

针对南阳煤业3#煤层厚度大、回采巷道断面大、支护困难等问题,采用理论分析、数值模拟的方法,确定了合理的巷道支护方案,并在3302轨道巷进行现场试验。对3302轨道巷巷道围岩变形量、顶板离层量及锚杆受力进行实时监测。现场监测数据显示,巷道围岩变形量不大,顶板无离层、失稳风险,锚杆受力状态良好,可有效约束巷道围岩变形。

Study on creep deformation and energy development of underground surrounding rock under four‐dimensional support

There is an urgent need to develop optimal solutions for deformation control of deep high‐stress roadways,one of the critical problems in underground engineering.The previously proposed four‐dimensional support(hereinafter 4D support),as a new support technology,can set the roadway surrounding rock under three‐dimensional pressure in the new balanced structure,and prevent instability of surrounding rock in underground engineering.However,the influence of roadway depth and creep deformation on the surrounding rock supported by 4D support is still unknown.This study investigated the influence of roadway depth and creep deformation time on the instability of surrounding rock by analyzing the energy development.The elastic strain energy was analyzed using the program redeveloped in FLAC3D.The numerical simulation results indicate that the combined support mode of 4D roof supports and conventional side supports is highly applicable to the stability control of surrounding rock with a roadway depth exceeding 520 m.With the increase of roadway depth,4D support can effectively restrain the area and depth of plastic deformation in the surrounding rock.Further,4D support limits the accumulation range and rate of elastic strain energy as the creep deformation time increases.4D support can effectively reduce the plastic deformation of roadway surrounding rock and maintain the stability for a long deformation period of 6 months.As confirmed by in situ monitoring results,4D support is more effective for the long‐term stability control of surrounding rock than conventional support.

龙泉煤矿大断面留顶煤回风巷道支护技术探讨

针对龙泉煤矿4号煤层4110回风巷大断面巷道布置及巷道支护问题,采用理论分析、数值模拟、井下试验等手段,对比分析大断面煤巷与以往小断面巷道围岩应力分布、破坏规律,探讨大断面留顶煤巷道围岩稳定性、围岩变形与破坏特征,并针对性优化大断面巷道支护方案。通过井下试验,验证优化后的巷道支护方案满足现场安全生产的需要,具有推广价值。

特厚煤层大断面软岩巷道底鼓治理措施与效果

以斜沟矿特厚煤层大断面软岩巷道反复强底鼓工程实际为背景,综合运用理论计算与现场监测方法,结合巷道底板岩层特性,判断巷道底鼓类型,引用巷道极限平衡理论,计算得出巷道极限平衡区最大深度为11.05 m,设计“双应力壳-梁”控制巷道底鼓措施。现场应用的监测结果表明,采用新的控制措施后,巷道底鼓量最大为17.49 cm,巷道底板围岩控制措施取得较好效果。

煤矿井下大埋深采区轨道巷支护技术研究与应用

深入探讨了大断面巷道支护技术在煤矿中的应用,分析了掘进区域的地质构造、煤层结构及巷道位置对支护方案的影响,并通过研究具体案例,明确了巷道尺寸、形状设计、地压和冲击地压等因素对选择支护方案的重要性。在实际应用中,针对研究区域的砾岩层和冲击地压危险区域,采用了高预应力强力锚杆锚索组合支护方式,并辅以喷射混凝土的联合支护方式,而且通过地质勘探和调整巷道尺寸,使得支护结构可以更好地适应煤层和地层的复杂变化,结果表明,该支护方案可以有效提高巷道的稳定性和安全性。

大倾角三软煤巷动态耦合支护技术研究及应用

大倾角三软煤巷掘进主要采用金属支架单一的刚性被动支护形式,支护效果较差,易发生变形。为了解决上述问题,研究一种大倾角三软煤巷动态耦合支护系统,在主支护结构中加入多个锚注时间指示装置,通过对三软煤巷进行地质力学评估,获取三软煤巷的多个原始地质力学参数,生成初始支护参数,现场设置支护系统并进行实时监测。根据动态地质力学参数和动态支护参数生成反馈信息,及时优化三软煤巷的动态地质力学参数和支护系统的动态支护参数,根据优化支护参数对支护系统中尚未设置好的部分进行修正。通过大倾角三软煤巷动态耦合支护方法及系统,得到最佳支护时间,以达到更好的支护效果。

大采高掘锚一体机升降操作平台的设计及应用

结合大采高煤巷锚杆支护现状,设计了一种机载升降操作平台,解决大采高断面锚杆支护难的问题,减轻工人劳动强度。现场使用表明,该升降操作平台极大提高了锚杆支护效率,具有一定的推广价值。

大倾角三软煤层回采巷道围岩变形破坏特性研究

采用相似模拟方法进行不同应力条件下大倾角煤层回采巷道的围岩破坏特性研究,结果表明,随着顶压系数k的增加,顶底板逐渐出现离层、剪切、滑移直至冒落,0≤k≤2时,锚网索支护起到了良好的锚固作用。k>2.5时,锚网索支护逐渐失效,巷道两帮中部及顶板中部破坏明显;随着顶压系数的增加,顶底范围的巷道分维数增速较快,增量显著,两帮范围的分维数D在增量和增速方面比顶底较低,说明顶底受顶压的影响大于两帮。顶板锚杆锚索轴力大于两帮,左侧顶部、帮部应力大于右侧;顶压系数0≤k≤2时,测点位移量较小,断面收缩率较低,锚网索支护效果较好,顶底板的变形量大于两帮,左侧(留三角煤处)变形量大于右侧,顶板及两帮中部变形量最大。

浅埋深大断面半煤岩巷快速掘进支护技术

研究浅埋深大断面半煤岩巷快速掘进支护技术对薄及中厚煤层的安全高效回采具有重要意义。以布尔台矿12203主运顺槽掘进工作面为研究对象,采用理论分析、工程类比和现场应用等方法,对巷道支护方式和支护设计原则进行了分析,提出了巷道围岩支护设计方案。针对巷道围岩变形(顶板下沉和两帮收敛)情况,验证了支护设计方案的有效性和可行性,提高了矿井的安全高效生产,同时也为其他煤矿的浅埋深大断面半煤岩巷的支护提供了技术方案。