“三软”低透气突出煤层瓦斯综合治理研究

＂三软＂低透气性突出煤层瓦斯抽放工作是目前国内瓦斯治理的难题.通过对永华公司二矿＂三软＂低透气性高瓦斯煤层影响因素的分析,提出了详细的煤巷掘进瓦斯抽放、采煤工作面瓦斯抽放及煤体注水的瓦斯综合治理方案,并进行了工业性试验.结果表明,采用此瓦斯综合治理方案后,掘进工作面及回风流的瓦斯体积分数保持在0.1%以下,工作面瓦斯抽放率达40%以上,工作面瓦斯体积分数控制在0.5%以下,工作面煤壁强度得到了强化,瓦斯涌出得到了控制,不仅提高了工作面的单产水平,而且煤巷掘进速度也达到了每月90 m以上,实现了工作面及煤巷的安全、快速推进.     

采煤工作面“爆注”一体化防突理论与技术

煤与瓦斯突出是深部高瓦斯矿井安全开采的最大障碍之一,回采工作面前方卸压区长度短、应力集中系数大、煤体干燥是诱发采面煤与瓦斯突出事故的主要因素.为了消除回采工作面突出危险性,提出了采面"爆注"一体化防突理论与技术——在采面前方应力集中区内实施爆破作业,降低煤体承载能力,迫使采面超前应力集中向深部推移,增大卸压区长度;通过爆破在应力集中区内产生新的煤层裂隙,促进新生裂隙和卸压区内裂隙连通,为应力集中区内煤层瓦斯释放提供了通道,降低煤层瓦斯含量;爆破能增加煤层裂隙,有效提高煤层注水效率,提高煤体的塑性,驱替煤层瓦斯流动、并抑制残余瓦斯解吸速度,降低突出危险性.研发的"爆注"一体化成套装备实现了同一钻孔内装药、水封耦合爆破、煤层注水的一体化安全高效作业;首创的水封耦合正向起爆方法能显著提高爆炸能量的利用率,并降低爆炸冲击波对封孔器的冲击力,有效延长封孔器的使用寿命.在平煤股份有限公司八矿孤岛工作面的试验结果表明:单个钻孔的"装药-封孔"一体化作业时间从传统40～60 min缩减到10～15 min;单个钻孔的封孔材料从约120 kg缩减到不足20 kg;"爆注"一体化作业实施后,采面超前应力峰向深部转移约6 m,卸压区长度显著增加,采面突出危险性降低;试验中用18个"爆注"一体化钻孔的消突效果和144个普通超前钻孔相当;单个钻孔注水量提升约23倍,煤层塑性显著提高,采掘过程中产生的粉尘浓度显著降低.     

综采工作面浅孔瓦斯抽放消突技术应用研究

针对平顶山煤业股份有限公司八矿己15突出煤层综采工作面一直存在抽放率低、排放钻孔消突效果差、瓦斯时常超限、制约安全生产等问题,试验利用工作面前方煤体透气性增加的动压区进行抽放的浅孔瓦斯抽放措施.根据防突安全要求、有关参数测定结果,并结合煤层赋存和施工技术条件,确定了合理的钻孔布置和抽放等关键技术参数.浅孔瓦斯抽放措施实施后,通过分析效果检验超标率、瓦斯体积分数和产量变化,考察了消突效果、抽放效果和生产效益.结果证明,浅孔瓦斯抽放措施技术可行,防突防瓦斯效果明显,是突出煤层采煤工作面解决瓦斯问题的有效途径之一.     

浅埋综采面高速推进对周期来压特征的影响

以活鸡兔井为工程背景,通过实测和理论分析就浅埋综采面高速推进对周期来压特征的影响规律进行了深入研究.结果表明:在高速推进情况下(推进速度一般大于10m/d),工作面周期来压持续长度显著增加,而周期来压步距、支架载荷和动载系数的变化相对较小.推进速度差异引起周期来压特征发生变化的实质是围岩变形破坏特征时间效应的体现.工作面高速推进时,直接顶由于推进速度较快垮落不充分,老顶在破断回转过程中需要更大的回转量才能触矸稳定,这是导致来压持续长度明显增加的重要原因.将推进速度对周期来压特征的影响规律运用到了神东矿区双回撤通道综采面末采段的让压开采实践中,指导了活鸡兔井21306综采面的安全回撤.     

巨厚火成岩对煤层瓦斯赋存及突出灾害的影响

通过采用火成岩取芯化验、煤样测试及现场观测等方法,分析了海孜煤矿10煤层覆岩中巨厚火成岩的力学性能,探讨了巨厚火成岩对远程10煤层瓦斯赋存与突出灾害的影响.结果表明:10煤层受巨厚火成岩的高温烘烤作用,煤体变质程度增高,煤层瓦斯吸附量增大,极限吸附量达到31.6753 m3/t;同时,巨厚火成岩均厚达120 m,单轴抗压强度平均为144.21 MPa,为矿井的主关键层,其阻碍了煤层瓦斯逸散,使煤层瓦斯含量高,且由于巨厚火成岩长期保持不断裂,导致10煤层工作面两端应力集中影响范围大大增加,达到100 m左右,更易具备煤与瓦斯突出的必要条件.     

地质构造突出机理研究

受煤层瓦斯压力差和煤层的透气性双重因素影响,煤层是瓦斯后期释放的主要通道. 当工作面出现断层、底凸时,这个释放通道会随煤层的变薄而变小,甚至于完全被封闭,地质构造阻碍和影响了煤层瓦斯的释放.地质构造的存在使瓦斯聚集,因此煤层遇到地质构造时容易造成瓦斯突出.当断层的落差基本等于煤层的厚度时将构成“最佳突出地质构造”, 它可以使突出的标高大幅度上移,也可以使突出的强度显著增大,该类构造也是我们应该特别注意防范的.     

地质构造突出机理研究

受煤层瓦斯压力差和煤层的透气性双重因素影响,煤层是瓦斯后期释放的主要通道.当工作面出现断层、底凸时,这个释放通道会随煤层的变薄而变小,甚至于完全被封闭,地质构造阻碍和影响了煤层瓦斯的释放.地质构造的存在使瓦斯聚集,因此煤层遇到地质构造时容易造成瓦斯突出.当断层的落差基本等于煤层的厚度时将构成"最佳突出地质构造",它可以使突出的标高大幅度上移,也可以使突出的强度显著增大,该类构造也是我们应该特别注意防范的.     

煤层注水促抽瓦斯及其影响因素的数值模拟

为有效预防煤矿瓦斯灾害,获取煤层注水促抽瓦斯的合理参数,以常村煤矿2103工作面为例,依据多相渗流理论,采用Fluent软件的VOF模型及多孔介质模型耦合求解,对煤层注水促抽瓦斯技术及其影响因素进行数值模拟,并将模拟结果应用于现场,对比分析数值模拟与现场实测数据,二者基本吻合.研究结果表明:煤层瓦斯含量以注水孔为中心径向逐步降低,以抽采孔为中心径向逐步升高;注水前抽采阶段,随着抽采时间的增加,抽采范围逐渐增大,抽采孔瓦斯流量先快速下降,后逐步缓慢降低;注水促抽阶段,随着注水时间的增加,注水范围逐渐增大,注水流量逐步降低,煤层瓦斯含量缓慢升高,抽采孔瓦斯流量逐渐增加;注水后抽采阶段,随着抽采时间的增加,压力水覆盖范围持续增大,煤层瓦斯含量逐渐降低,抽采孔瓦斯流量逐渐减小.注水时机、注水时间、注水压力、注水方式、布置方式及钻孔间距是影响煤层注水促抽瓦斯效果的6个主要因素.瓦斯正常抽采20 d后,按照一注一抽方式及5 m间距布置注抽钻孔,在8 MPa煤层注水压力下间歇注水10 d,煤层注水促抽瓦斯效果较好.     

基于在线监测的三软煤层综采工作面矿压显现规律研究

针对郑州矿区三软煤层出现的煤巷锚杆被剪断、工作面两巷表面位移大和综采工作面矿压显现规律不清晰等情况,以芦沟煤矿32081综采工作面为工程背景,应用KJ21煤矿顶板灾害监测预警系统对该工作面及两巷矿压进行在线监测,分析研究芦沟煤矿综采工作面周期来压步距、巷道围岩显现规律和超前支承应力分布规律。研究得出如下结论:芦沟煤矿选用ZF3000/17/27型液压支架能满足支护要求,综采工作面平均周期来压步距为11.16 m,沿空掘巷煤柱最佳宽度为3 m,综采工作面两巷超前加固距离不应少于50 m,为矿井综采工作面支架选型和煤巷锚网支护设计提供了科学依据,有效保障了矿井安全生产。     

新庄孜矿B8保护层开采对B6煤效果考察实践分析

以突出矿井新庄孜矿为例,介绍了煤层群开采首采保护层卸压瓦斯抽采工程设计及被保护层瓦斯抽采效果。通过在66208工作面回采过程中瓦斯压力测定、瓦斯抽采效果和煤层最大变形量的考察,得出保护层工作面开采后,被保护层B_6煤层透气性系数增大了902倍,B_6煤层残余瓦斯含量为2.43 m~3/t;得出实际走向及倾向方向上的有效保护范围。最大化的回收煤炭资源,取得了较好的效果。     

利用固体充填开采方法保护建筑群安全的研究

我国煤矿建筑物下压煤量占总压煤量的69%,同时每年要向地面排放4.5亿t以上的固体废弃物,因此,研究利用固体废弃物充填开采方法,在保证地表建筑物安全性的基础上,高效开采出下压煤炭资源意义重大.文章应用数值模拟方法,对建筑物下压煤开采所引起的岩层移动过程进行模拟,系统分析了采场围岩塑性区分布及地表沉陷量变化规律,由计算结果分析得知,应用固体充填开采法与无充填直接开采相比,采场围岩破坏单元数较少,围岩稳定性受影响较小,减少地表沉陷量效果明显.以数值模拟结果作为参考,研制了长臂综采矸石充填开采工艺的配套设备,并在某矿建筑物下压煤炭开采的实际应用中取得良好效果,有效控制了地表变形,保证了建筑物的安全性和资源的高效开采.     

煤矿绿色开采技术

提出了煤矿绿色开采的概念，阐述了它的内涵和技术体系，绿色开采的理论基础为：开采后岩层中的关键层运动形成的节理裂隙与离层规律以及瓦斯与地下水在破断岩层中的渗流规律。绿色开采技术的主要内容包括：保水开采、建筑物下采煤与离层注浆减沉、条带与充填开采、煤与瓦斯共采、煤巷支护与部分矸石的井下处理、煤炭地下气化等。     

Surrounding rock control of gob-side entry driving with narrow coal pillar and roadway side sealing technology in Yangliu Coal Mine

Gob-side entry driving can increase coal recovery ratio, and it is implied in many coal mines. Based on geological condition of 10416 working face tailentry in Yangliu Coal Mine, the surrounding rock deformation characteristics of gob-side entry driving with narrow coal pillar is analysed, reasonable size of coal pillar and reasonable roadway excavation time after mining are achieved. Surrounding rock control technology and effective roadway side sealing technology are proposed and are taken into field practice. The results showed that a safer and more efficient mining of working face can be achieved. In addition, results of this paper also have important theoretical significance and valuable reference for surrounding rock control technology of gob-side entry driving with narrow coal pillar under special geological condition.     

综放开采顶板冒落撞击摩擦火花引爆瓦斯研究

针对康家滩煤矿8^#煤层综放开采条件，采用专门设计的实验装置对其顶板冒落撞击摩擦火花引爆瓦斯的可能性进行了实验研究．结果表明：冒落岩石的质量、冒落岩石撞击高度与角度、岩石性质及砂岩中的石英含量、岩石的潮湿度等是影响岩石撞击摩擦火花温度及其能否引爆瓦斯的重要因素．当石英砂岩间在接触压力迭171．2N以上、以10m／s的速度摩擦，在2～30s内可引起瓦斯爆炸．康家滩煤矿8^#煤层局部区域的石英砂岩冒落撞击高度最大达6．76m，撞击速度可达11．51m／s，具有引爆瓦斯的可能性．     

Numerical simulation study on hard-thick roof inducing rock burst in coal mine

In order to reveal the dynamic process of hard-thick roof inducing rock burst, one of the most common and strongest dynamic disasters in coal mine, the numerical simulation is conducted to study the dynamic loading effect of roof vibration on roadway surrounding rocks as well as the impact on stability. The results show that, on one hand, hard-thick roof will result in high stress concentration on mining surrounding rocks; on the other hand, the breaking of hard-thick roof will lead to mining seismicity, causing dynamic loading effect on coal and rock mass. High stress concentration and dynamic loading combination reaches to the mechanical conditions for the occurrence of rock burst, which will induce rock burst. The mining induced seismic events occurring in the roof breaking act on the mining surrounding rocks in the form of stress wave. The stress wave then has a reflection on the free surface of roadway and the tensile stress will be generated around the free surface. Horizontal vibration of roadway surrounding particles will cause instant changes of horizontal stress of roadway surrounding rocks; the horizontal displacement is directly related to the horizontal stress but is not significantly correlated with the vertical stress; the increase of horizontal stress of roadway near surface surrounding rocks and the release of elastic deformation energy of deep surrounding coal and rock mass are immanent causes that lead to the impact instability of roadway surrounding rocks. The most significant measures for rock burst prevention are controlling of horizontal stress and vibration strength.     

大采深条带开采坚硬顶板工作面冲击矿压治理研究

为了解决大采深条带开采坚硬顶板工作面的冲击矿压问题,以古城煤矿2106工作面为例,采用现场分析、实验室试验、数值模拟的方法对其发生机理进行了研究.结果表明在此条件下开采时发生的冲击矿压与煤岩性质、采深、坚硬顶板厚度及顶板的周期来压有密切关系.当冲击矿压发生的煤层具有强冲击倾向性,煤层硬度系数大于3、采深900 m以上、顶板岩层坚硬且厚度大于20 m时,冲击矿压发生具有突然性和猛烈性;主要发生在顶板周期来压期间、超前支护50m范围内,此时工作面的CH4和CO气体含量同时升高.对此提出了钻屑法等预测预报的方法和煤体爆破卸压与柔性支护等治理措施.     

Dynamic failure risk of coal pillar formed by irregular shape longwall face:A case study

Irregular shape workface would result in the presence of coal pillar, which leads to high stress concentration and possibly induces coal bumps. In order to study the coal bump mechanism of pillars, static and dynamic stress overlapping(SDSO) method was proposed to explain the impacts of static stress concentration and tremors induced by mining activities. The stress and deformation in surrounding rock of mining face were analyzed based on the field case study at 1303 workface in Zhaolou Coal Mine in China.The results illustrate that the surrounding rock of a workface could be divided into four different zones,i.e., residual stress zone, stress decrease zone, stress increase zone and original stress zone. The stress increase zone is prone to failure under the SDSO impact loading conditions and will provide elastic energy for inducing coal bump. Based on the numerical modelling results, the evolution of static stress in coal pillar as the size of gob increasing was studied, and the impact of dynamic stress was investigated through analyzing the characteristics of tremor activities. The numerical results demonstrate the peak value of vertical stress in coal pillar rises from about 30 MPa with mining distance 10 m to 52.6 MPa with mining distance 120 m, and the location of peak stress transfers to the inner zone of coal pillars as the workface moves forward. For the daily tremor activities, tremors with high energy released indicate high dynamic stress disturbance on the surrounding rock, therefore, the impact of dynamic stressing is more serious during workface extension period because the tremor frequency and average energy after workface extension are higher than those before the workface extension.     

深部巷道围岩变形试验与数值模拟研究

为了研究深部软岩巷道的变形破坏特性,以淮南矿区某煤矿13-1煤回采巷道为例,在现场调查回采巷道工程概况的基础上,开展了室内深部回采巷道围岩变形特性相似模拟试验,并基于块体离散元法,建立了深部回采巷道围岩的数值模型,模拟了开挖过程中围岩的变形特性。相似模拟试验和数值模拟试验结果表明,深部巷道围岩的典型特征为:巷道底臌量两帮移近量顶板下沉量,巷道不同围岩受开挖扰动的位移影响范围不同,底板为3.5 m,顶板为2.45 m,两帮为5.5 m。     

Systematic principles of surrounding rock control in longwall mining within thick coal seams

Effective surrounding rock control is a prerequisite for realizing safe mining in underground coal mines.In the past three decades, longwall top-coal caving mining(LTCC) and single pass large height longwall mining(SPLL) found expanded usage in extracting thick coal seams in China. The two mining methods lead to large void space left behind the working face, which increases the difficulty in ground control.Longwall face failure is a common problem in both LTCC and SPLL mining. Such failure is conventionally attributed to low strength and high fracture intensity of the coal seam. However, the stiffness of main components included in the surrounding rock system also greatly influences longwall face stability.Correspondingly, surrounding rock system is developed for LTCC and SPLL faces in this paper. The conditions for simultaneous balance of roof structure and longwall face are put forward by taking the stiffness of coal seam, roof strata and hydraulic support into account. The safety factor of the longwall face is defined as the ratio between the ultimate bearing capacity and actual load imposed on the coal wall.The influences provided by coal strength, coal stiffness, roof stiffness, and hydraulic support stiffness,as well as the movement of roof structure are analyzed. Finally, the key elements dominating longwall face stability are identified for improving surrounding rock control effectiveness in LTCC and SPLL faces.