煤层高压注水防治煤与瓦斯突出效果考察及机理分析

为了深入探讨煤层高压注水的防突出机理,采用地应力分布、瓦斯解吸速度和钻屑瓦斯解吸指标K1值作为研究指标,考察了阳泉煤业集团新景矿煤层高压注水后的防突效果,结合实测数据对煤层高压注水的防突机理进行了分析.研究表明,煤层高压注水具有如下2种效应:一是高压水破裂煤体,使煤体塑性增加,导致集中应力带前移;二是注水后残留的水分对煤体瓦斯解吸有抑制效应,可避免煤体瓦斯快速解吸.2种效应同生共存,共同对煤与瓦斯突出产生防治作用.     

煤层注水防突最优润湿时间试验研究

煤层注水就是通过钻孔将压力水注入煤体,使煤、瓦斯和水之间产生复杂的三相耦合作用,以降低煤炭开采时煤尘生成量并防止煤与瓦斯突出.煤矿采用煤层注水防突措施后,何时进行采掘作业,长期以来缺少可靠的判断方法.针对此问题,在实验室通过测定煤层注水后不同润湿时间下预先吸附瓦斯煤样的解吸速度,根据煤、水充分润湿后水与煤体中孔隙的毛细作用和抑制瓦斯解吸效应最强原理,以第一分钟瓦斯解吸速度V1及解吸速度衰减系数k t作为研究指标,在特定试验条件下,计算得到超化、古汉山和寺河等煤矿煤样的最优润湿时间,分别为6.44,7.00,10.41 h.最后,结合各煤样的注水相关参数,论证证明最优润湿时间确定方法是可行的,该方法对煤层注水防突技术参数优化具有重要的指导意义.     

基于NMR的低渗煤体自渗吸实验研究

基于煤层注水对提高煤层气采收率、防治瓦斯灾害的重要性,研究了低渗煤体在自渗吸过程中的微观渗流特征.采用核磁共振(NMR)技术监测煤样在自渗吸实验中的T2谱与一维频谱,得到了煤体在不同时刻、不同位置的一维水信号分布情况.结合孔隙结构,通过核磁法从微观角度分析吸水量和含水量的时间与空间演化规律.结果表明:在快速上升阶段与缓...     

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.     

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.     

不同煤体结构煤的f值分布特征

以淮南煤田C13-1煤层不同煤体结构类型煤的118个坚固性系数(f值)测定资料为基础,分析了不同煤体结构煤的f值分布特征和统计规律,说明了煤体破坏与f值的相互关系,并提出将f值作为硬煤和构造软煤的分类指标.     

不同煤体结构煤的f值分布特征

以淮南煤田C13-1煤层不同煤体结构类型煤的118个坚固性系数(f值)测定资料为基础,分析了不同煤体结构煤的f值分布特征和统计规律,说明了煤体破坏与f值的相互关系,并提出将f值作为硬煤和构造软煤的分类指标.     

煤层波谱特征与瓦斯含量的试验研究

为研究煤层频谱特征与煤层瓦斯地质参数间相关关系,选取几个典型矿区的主采煤层,采用矿井震波探测技术进行原位煤体震波波谱探测实验．试验结果表明,煤体波谱特征反映了煤层本身的物理力学性质,同一结构的煤层在其5倍厚度的距离内煤壁的主频值相对稳定．主频的变化反应了煤体结构的特征,结构破坏主频明显低移;不同的煤层具有不同的主频,突出煤层具有低主频特征．煤层瓦斯含量与煤层固有主频成较好的线性相关,煤层固有主频值越低,相应煤层瓦斯含量越高．研究结果可为煤与瓦斯突出预测提供新的方法．     

顶板岩层对冲击矿压的影响规律研究

采用模拟试验方法研究了顶板岩层对煤体应力状态的影响,并根据震动能量对煤体的破坏效应和在岩体中的传播衰减规律,从能量角度分析了煤层上方不同厚度和强度的顶板岩层对煤体冲击的影响程度.结果表明,顶板释放的能量与岩层强度呈对数关系、与顶板厚度呈指数关系,坚硬、厚层顶板岩层会对煤体产生更为强烈的扰动,使冲击矿压危险性明显升高.另外,具有一定厚度和强度且距离煤层较近的老顶岩层运动产生的冲击载荷对煤体的影响作用较大.某矿一个工作面的冲击矿压防治工程实践表明,对该煤层上方的顶板岩层实施爆破弱化处理技术措施后,可有效降低工作面回采过程中的冲击危险性.     

超临界CO_2提高煤层渗透性的增透规律研究

基于Peng-Robinson状态方程,考虑了CO2在不同温压下密度和黏度的变化对超临界CO2在低渗透煤层中渗透性的影响,利用自制三轴渗透仪进行不同温压条件下超临界CO2的增透实验,增透实验前后分别进行甲烷的渗透率测试.结果表明:超临界CO2作用后,煤体对甲烷的渗透率较增透实验前提高了一个数量级;超临界CO2的密度和黏度随孔隙压力的增加均呈指数递增的变化规律;在恒定温度下,超临界CO2的渗透率随着孔隙压力的增加呈指数递增的变化趋势;煤体微观孔隙、裂隙的CT扫描图显示超临界CO2作用后,煤体微观孔隙、裂隙较增透前尺寸明显增大、密度增加、连通性提高,说明由于超临界CO2的作用,进一步促进了煤层微观孔隙、裂隙的有效发育,增大了渗流空间,提高了煤层的渗流能力.     

Application of coal mine roof rating in Chinese coal mines

The coal mine roof rating(CMRR) is a measure of roof quality or structure competency for bedded roof types typically of underground coal mines. The CMRR has been used widely in the US, South Africa,Canada and Australia. In order to investigate the application of the CMRR system in Chinese coal mines,two coal mines in China located in Panjiang Coal Field in Guizhou Province were investigated. Field data were collected which is required to calculate the CMRR value based on underground exposure. The CMRR values of 11 locations in two coal mines were calculated. The investigations demonstrated that the chance of mine roof failure is very low if the CMRR value is more than 50, given adequate support is installed in mine. It was found that the CMRR guideline are useful to preliminarily investigate stability in Panjiang Coal Field mines.     

Anisotropic coal permeability and its stress sensitivity

This paper focuses on anisotropy of coal permeability and its stress sensitivity. Coal blocks were taken from Xinjing Coal Mine in Yangquan Coal District. Coal cores were then drilled along the strike, dip, and vertical directions. Coal permeabilities were measured with respect to stress by using a self-developed coal permeability measurement system. The used samples exhibited significant permeability anisotropy.The permeability along the strike direction was greatest among the three directions, the permeability along the vertical direction was the smallest, and the permeability along the dip direction was between the other two directions. The sensitivity of coal permeability to stress was transversely isotropic. The stress sensitivity coefficient was greater along the horizontal directions than along the vertical directions.Coal permeability exhibited anisotropic stress sensitivity due to anisotropy in Young's modulus and porosity. The results obtained in this study are useful for optimizing the arrangement of pre-drainage boreholes.     

福建省仙亭煤矿水平延深工程探讨

通过对福建上京矿务局仙亭煤矿第一水平煤炭资源揭露情况和该矿开采现状的分析 ,从煤炭销售、矿井资源条件、经济开采规模和现有水平周边井田资源开发利用情况等方面 ,深入探讨了仙亭煤矿水平延深的必要性 ,并提出了实施思路 .结果对指导仙亭煤矿水平延深工程的设计和实施具有重要意义 ,可供福建省煤矿水平延深工程借鉴 .     

Performance of cemented coal gangue backfill

Possibility of cemented gangue backfill was studied with gangue of Suncun Coal Mine, Xinwen Coal Group, Shandong, and fly ash of nearby thermal power plant, in order to treat enormous coal gangue on a large scale and to recovery safety coal pillars. The results indicate that coal gangue is not an ideal aggregate for pipeline gravity flow backfill, but such disadvantages of gangue as bad fluidity and serious pipe wear can be overcome by addition of fly ash. It is approved that quality indexes such as strength and dewatering ratio and piping feature of slurry can satisfy requirement of cemented backfill if mass ratio of cement to fly ash to gangue is 1：4：15 and mass fraction of solid materials reaches 72%-75%. Harden mechanism suggests that the cemented gangue fill has a higher middle and long term comprehensive strength.     

Developing coal burst propensity index method for Australian coal mines

Coal burst is the violent failure of overstressed coal, and it is often accompanied by sound, coal ejection and seismic events. It is subsequently recognized as a serious safety risk of Australia after double fatalities coal burst happened at Austar Coal Mine. Considering the increasing trend of coal burst severity and frequency with mining depth, it is an urgent task to develop the coal burst risk assessment methods for Australia underground coal mines. Coal burst propensity index method is a widely used method of burst risk evaluation of coal as it is summed up from the coal burst research and practice of many countries.This paper presents the experimental and theoretical research of coal burst propensity index method for coal burst risk assessment in Australia. The definition of four indexes including elastic strain energy index(W_(ET)), bursting energy index(K_E), dynamic failure time(DT) and uniaxial compression strength(RC)is introduced in the first part. Then, the standard laboratory test process and test parameter of coal burst propensity index is presented. DT test is conducted with 0.3 mm/min displacement control loading rate while other test is with 0.5 mm/min. Besides, modified data processing and risk classification method of test are proposed. Differentiate analysis of stress-strain curve is adopted in the data processing of DT and KEindex. A four level risk classification form of burst risk is recommended for Australian underground coal mines. Finally, two likely improvement methods of W_(ET) test, including volumetric strain indicator method and theoretical calculation method, are discussed.     

A review of cavability evaluation in longwall top coal caving

Longwall Top Coal Caving has been considered as one of the most effective technologies for the extraction of underground thick coal seams. A large number of studies on the applicability of Longwall Top Coal Caving into new mine sites have linked the success of its application to the geo mechanical understanding of the cavability of the top coal. The paper aims to improve the knowledge of the top coal cavability evaluation. A range of parameters that affect the top coal cavability were first identified. Afterward, a number of cavability assessment methods and classifications were reviewed. The result is important in that it assists researchers in developing an advanced and reliable tool for the top coal cavability evaluation.     

粉煤灰廉价吸附剂资源化利用的现状和对策分析

粉煤灰是燃煤电厂排放的固体废弃物,其大量堆积造成环境污染和资源浪费,对粉煤灰的资源化利用近年来引起人们的广泛关注.粉煤灰呈多孔结构,具有良好的吸附性能,可用作处理废水中污染物质的廉价吸附剂.本文对粉煤灰吸附剂在水污染治理中的研究现状进行分析和总结,在此基础上,根据粉煤灰的组成和性质,提出粉煤灰资源化利用的方向为化学处理提高吸附性能和成型造粒以利于其工业化利用.     

平顶山构造复杂区煤、岩层高精度对比

平顶山煤田石炭二叠纪含煤八组共 60余层 ,煤层间距近、分叉合并现象普遍 ,因煤层对比不准确而影响生产的现象时有发生 .文中应用近年来出现的层序地层学对比技术 ,对该煤田西部构造复杂区 ,主要可采煤层丁、戊、己三个煤组 ,进行了高精度的煤、岩层对比 .应用这一技术 ,可在对比剖面图上预测到落差大于 6 3～ 7 6m的断层 ,因而有利于巷道开拓、采掘的正确部署     

木城涧煤矿异常条件下回采底分层空间模拟试验研究

通过对北京矿务局木城涧煤矿不具备常规条件下十槽煤底分层的相似材料模拟试验研究 ,证明了回采上分层时顶板冒落情况和矿压显现规律 ,初步探明了留与不留煤皮假顶情况下 ,回采下分层时顶板岩层二次失稳情况和矿压显现规律 ,为类似条件下开采底分层制定合理的回采方案、安全技术措施等提供重要的依据     

煤炭自燃标志性气体预测指标的实验研究

设计并研制了氧化热解实验模拟装置，通过对峰峰矿区小屯矿工作面采空区煤样的氧化热解模拟实验，绘制了各氧化热解气体CO2、O2、C2H6和CO等气体浓度随温度的变化曲线，并对其分析找出了该矿采空区煤炭自燃的标志性气体预测指标，从而为掌握工作面采空区煤炭自燃的规律和制定有效合理的煤炭自燃发火的防治措施提供依据，为煤矿的高效生产提供安全保障。