High prestress truss cable support principle and its application in large cross section coal roadway

With the enlarge of cross section of roadway, the radius of plastic area and broken area increase, and the tensile stress and shear stress distributing in roof coal-rock layers relevantly increase, which induce support effect not obvious for ordinary bolt（cable）. While bounding point and support structure of the truss cable is in vertex angle of roadway, and supplies coal-rock layers in bounding area with the horizontal and vertical pressure, so it settles the support problems in large cross section coal roadway. From the point of view of mechanics, gave emphasis on the invalid mechanics of ordinary bolt （cable） in large cross section coal roadway and supported mechanics of prestress truss cable. The author successfully used this technique in Wuyang Mine, and had the huge economic efficiency and the social benefit.

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.

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.

Semi-Industrial Test of Underground Coal Gasification In Well No.2 in Xinhe, Xuzhou

The necessity of underground coal gasification is explained. The condition,technology character,and process of the semi-industrial test of underground coal gasification in well No. 2 at Xinhe, Xuzhou,are introduced. The test results indicate that the technique of long tunnel,large sectiou,two stage underground coal gasification can obtain a large output of coal gas with a high heat value, making the working process stable. So the feasibility of the new techuology is verified. It can be concluded that there will have a good application prospect of the technique in China.

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。

新景矿大断面岩巷综掘技术研究与应用

为提高掘进速度,保证巷道稳定,在新景矿15号煤采区集中辅助运输巷开展了大断面岩巷综合机械化掘进技术的研究。在分析当前施工工艺以及支护中存在问题的基础上,提出了以EBZ320D掘进机和CMM2-25型锚杆钻机为主要设备的综合机械化岩巷掘进作业线。理论分析了锚杆索围岩强度强化理论,结合现场实际情况,设计了以不同长度锚索为主的支护方式。现场应用表明,应用新的综合机械化掘进技术后,巷道变形量小,掘进速度快,施工成本低,经济社会效益显著,应用效果良好。

煤矿掘进巷道断面尺寸变化对噪声传播的影响

为研究煤矿掘进巷道长空间内断面尺寸变化对噪声传播的影响,采用仿真模拟方法研究巷道内噪声传播,分析煤矿掘进巷道断面积大小、断面形状及断面面积突变率的变化对巷道内噪声传播影响。结果表明:煤矿掘进巷道内断面面积大小、断面形状及断面面积突变率均会影响巷道内噪声的传播,当噪声源功率、频率相同时,声压级衰减随巷道截面积增大而增大;对于给定的断面面积(18 m2),当断面形状不同时,声压级衰减也不同,且断面形状为拱形时会产生明显的声聚焦效应,不利于噪声衰减;当断面面积发生突变时,巷道内的声压级分布会有所变化,其中断面面积由大变小时不利于噪声的衰减,断面面积由小变大时仅影响突变后的声场,而对巷道内整体声压级影响并不明显;巷道内噪声衰减现场测试与数值模拟结果基本一致,验证了搭建的模型及模拟结果的可靠性。

非对称载荷作用下倾斜区段煤柱稳定性分析及控制技术

为解决工作面回采及巷道掘进影响下倾斜区段煤柱稳定性劣化的复杂问题,运用弹性力学半逆解法及摩尔-库伦准则建立力学模型,结合三维有限元数值模拟,深入分析了倾斜区段煤柱一侧受载结构形态特征,明确了倾斜煤柱失稳致灾力源及载荷的分布特性,探究了采掘扰动下倾斜区段煤柱塑性变形-失稳-破坏的动态演化过程,揭示了非对称载荷作用下倾斜区段煤柱临界失稳致灾机理,以此为基础优化了倾斜煤柱及周围巷道稳定性控制技术。结果表明:区段煤柱因煤层倾角导致的倾斜形态是煤柱所承受载荷呈非对称状的关键诱因,这一特性致使倾斜煤柱最底端区域覆载最大,且当此区域失稳破坏时,呈现由煤柱下端底角塑性区向煤柱上端底角塑性区扩展的运移过程,并因此得出倾斜区段煤柱临界尺寸随煤层倾角增大而增加的演化规律。由此,针对大南湖一矿倾斜区段煤柱及周围巷道变形失稳的问题,采用支护优化及注浆加固等措施,降低了倾斜区段煤柱侧巷道的变形速率,为类似矿井的煤柱稳定性控制提供了借鉴。

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。

高地应力缓斜半煤岩巷道断面形状优化研究

为了优化高地应力缓斜半煤岩巷道的断面形状,以东欢坨矿3018工作面运道为工程背景展开研究。通过复变函数理论推导得出了倾斜煤层中不同断面形状的应力解析解,然后运用FLAC3D数值模拟求解了不同断面形状巷道的应力集中和塑性区情况,并以此为基础确定了巷道最优断面形状,最后结合现场工业性试验对研究结果的可靠性进行了验证。研究结果表明:高地应力作用下缓斜半煤岩巷道破坏呈现非对称形式;不管断面形状如何,巷道均在左、右两底角处呈现高应力集中,且应力集中程度矩形>梯形>直墙拱形;直墙拱形巷道稳定性最佳,梯形巷道次之,矩形稳定性最差,确定直墙拱形为最终巷道断面形状;现场巷道表面位移量监测结果表明,直墙拱形巷道更能满足现场安全生产要求。

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。

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。

综放面“双硬”煤层临空煤柱宽度及承载强度校核

具有“双硬”特征煤层的工作面其护巷煤柱的极限尺寸确定与常规工作面有所不同。以榆树岭煤矿505工作面沿空掘进巷道为背景,首先测试了煤岩样的力学性质和不同高径比煤样的抗压强度,得到了不同高径比煤样峰值强度曲线;其次分析了沿空掘巷覆岩结构模型,建立了沿空掘巷护巷煤柱顶板力学模型,得到了不同宽度煤柱所受的载荷应力;建立了不同高宽比煤柱的数值模型,得到了不同高宽比煤柱的极限强度校核公式;最后通过对比不同宽度煤柱所受的载荷应力和极限强度,得出4m宽度的煤柱即可满足支护要求,并在此基础上提出了沿空掘进巷道支护工艺。现场监测结果表明,煤柱宽度为4m时,巷道整体变形量较小,巷道稳定性得到有效维护。研究结果可为小煤柱护巷宽度的确定提供参考。

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。

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。

高应力大断面巷道围岩注浆加固机理及其应用

为解决高应力大断面巷道服务期间变形严重的问题,利用莫尔-库仑准则和力学平衡原理,开展巷道松动圈注浆加固机理和力学模型分析,采用FLAC3D仿真计算软件对4种不同支护形式进行数值模拟,研究不同支护状态下巷道变形演化规律,并开展现场工程实践。研究结果表明:增加承载层的长度可以有效提高巷道围岩的稳定性,注浆加固可黏合破碎岩体,形成骨架结构;分层掘进可减小巷道围岩自由面,从而减缓应力释放速度;滞后注浆可在应力基本释放后对破碎岩体进行最大程度的黏合加固,加固后的松动圈形成整体结构后配合锚杆索支护,能够有效减少围岩破坏以及塑性区发育。实践证明:采用“分层掘进+滞后注浆+锚索补强”支护方案后,掘进期间,顶底板最大移近量约为50 mm,两帮最大移近量约为140 mm,底鼓量约为75 mm;5303工作面回采期间,顶底板最大移近量约为125 mm,两帮最大移近量约为350 mm,底鼓量约为173 mm,虽然回采期间巷道变形量较大,但整体变形可控,能满足深部大断面巷道支护要求。“分层掘进+滞后注浆+锚索补强”支护方案能够有效解决高应力大断面巷道严重变形问题,可在类似地质条件的矿井推广。

巷道三维激光点云数据变形提取方法

在地下煤炭资源开采过程中,高地压、高应力等外部因素会使得巷道围岩出现形状改变并引发冒顶、片帮等围岩破坏现象,严重威胁煤矿安全生产。为及时掌握巷道围岩变形情况,对煤矿巷道变形进行有效监测,提出了一种基于三维激光点云技术的巷道断面提取与变形量分析方法,并通过巷道内模拟实验验证了该方法的可行性。实验结果表明:所提方法能够适应井下巷道复杂环境,自动识别巷道变形位置并利用断面提取法进行更精确的变形分析,所监测表面位移分辨率能够达到厘米级,符合巷道表面位移监测需求。

深部巷道大断面交叉点联合支护技术研究

针对深部大断面巷道支护易发生失稳的难题,以唐山矿-1100中央轨道山下车场大断面交叉点为工程背景,开展工程地质调查及巷道变形情况分析,提出锚喷+锚注联合支护方案,并运用FLAC3D数值模拟分析支护方案改进前、后巷道变形情况。结果表明,常规锚网喷支护下大断面巷道顶板下沉和帮部位移量较大,巷道不能实现自稳;锚喷+锚注联合支护下巷道变形量大幅降低,巷道基本实现自稳。将该方案应用于工程实践,锚喷+锚注联合支护技术能够有效控制深部大断面巷道变形,顶板下沉量较原支护降低了78.8%,帮部位移量降低了54.8%,为同类工程背景提供可靠的技术参考。

松软破碎厚顶煤大跨度切眼变形破坏特征与控制技术

安阳主焦煤矿大断面切眼常采用被动支架沿顶布置,围岩变形量大、易漏冒,工人劳动强度大。针对上述问题,采用数值模拟方法研究了裂隙发育、位移和应力分布与切眼跨度之间的关系,提出了围岩控制策略和支护方案。结果表明,随着切眼跨度的增大,围岩塑性区范围逐渐增加,顶板以剪切滑移或拉剪破坏为主,两帮以泊松效应膨胀拉伸—剪切破坏为主;顶板下沉量、巷帮内挤和底鼓量均逐渐增大;顶煤、直接顶和基本顶部分岩层逐层渐次移动,顶板部分区域出现较大的裂隙,冒落拱以上深部顶板发生整体移动;巷道顶底板中有害拉伸应力区域范围呈现拱形分布,且逐渐增大。根据切眼围岩变形破坏特征,提出了高强度、高刚度、高预紧力的强力支护和被动单体液压支柱补强的主被动联合支护方法。现场工业性试验表明,切眼围岩得到了有效控制,可为类似裂隙发育托顶煤大断面切眼围岩控制提供参考。

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。