突出矿井煤层群开采首采保护层区域消突技术实践

以突出矿井谢桥煤矿为例,介绍了煤层群开采首采保护层卸压瓦斯抽采工程设计和被保护煤层卸压瓦斯抽采效果.实践表明,谢桥矿1242(1)保护层开采实践证明,在11-2煤层有效保护范围内的13-1煤层,可充分消除其突出危险性,并有利于被保护层瓦斯治理;经保护层开采后,不仅能最大程度消除高瓦斯突出危险煤层的瓦斯事故隐患,而且极大地提高了巷道掘进速度,从而缓解了工作面接替的紧张局面,有效提高了生产效率.保护层开采区域消突技术是防治煤与瓦斯突出最经济、有效的技术措施.     

煤层群煤与瓦斯安全高效共采体系及应用

提出了高瓦斯煤层群煤与瓦斯安全高效共采的概念：在煤层群开采条件下，首先开采瓦斯含量低、无突出危险的首采煤层，利用其采动影响使处在其上部和下部的煤层卸压，煤层透气性成百倍地增加，从而形成高效的瓦斯抽采条件．同时进行的卸压瓦斯高效抽采既解决了由卸压煤层向首采煤层涌出瓦斯问题，保障首采煤层实现安全高效开采，又大幅度地降低了卸压煤层的瓦斯含量，消除了煤与瓦斯突出危险性，为在卸压煤层内实施快速掘进与高效采煤方法提供了安全保障，从而实现了瓦斯与煤炭两种资源的安全高效共采．文中介绍了针对不同卸压瓦斯流动特点的近程、中程和远程卸压瓦斯抽采方法及工程应用实践，最后对高瓦斯煤层群煤与瓦斯安全高效共采体系的应用前景进行了分析．     

煤层群首采关键层煤与瓦斯共采技术研究

基于新庄孜煤矿近距离煤层群全为突出煤层的情况,选择突出危险性程度较低的、煤层厚度只有0．8m的B10煤作为近距离煤层群开采首采层,即关键保护层工作面。采用一面六巷的瓦斯治理技术,并在66310工作面成功应用,实现了煤层群首采关键层煤与瓦斯安全高效共采。研究成果可为低透气性高瓦斯煤层群卸压开采提供指导。     

急倾斜近距离下保护层开采岩层移动相似模拟

针对豫西某矿急倾斜近距离下保护层开采设计,以矿井现场工程概况为基础,通过相似模拟试验及现场考察,对保护层开采过程中岩层移动变形及裂隙发育进行研究,据此分析该矿急倾斜近距离下保护层开采的可行性及预期卸压效果。结果表明:保护层开采过后,顶板以缓慢下沉为主,未出现大规模垮落,岩层移动量最大位置位于倾斜中部略偏上;相似模拟所得倾斜下部卸压角为73°,现场考察倾斜下部卸压角为72°,《防治煤与瓦斯突出规定》中在煤层倾角为50°情况下倾斜下部卸压角参考值为70°,三者高度吻合;岩层移动以及裂隙发育使被保护层得以卸压,也可为卸压瓦斯运移和瓦斯抽采提供通道;被保护层开采条件不会破坏,该矿此类型保护层开采安全可行,可以达到预期防突效果。     

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。     

红菱煤矿开采保护层对 煤岩体透气性的数值模拟

以红菱煤矿保护层开采为工程实例,通过开采11#煤层,对存在煤与瓦斯突出的7#煤层和12#煤层进行 卸压,利用FLAC3D数值模拟中小同步开挖的渗透率变化情况,对保护层开采过程中煤岩体的渗透性进行了分 析,得出了煤岩体透气性变化规律。结果表明:煤岩体的透气性随着工作面推进不断增强;开采保护层上覆岩体 的渗透率明显比底板岩体的渗透率大;卸压效果越好,渗透率越大。     

地面群孔瓦斯抽采技术应用研究

为保证新集一矿突出煤层13-1煤北中央采区的安全开采,先后开采131103、131105等11-2煤层工作面作为保护层。首先在上述两个工作面共布置了6个地面钻孔,建立了地面群孔瓦斯抽采系统,预抽采动区被保护层13-1煤瓦斯。接下来对地面钻孔抽采瓦斯参数进行了考察,主要包括基于示踪技术考察了131105工作面采动卸压地面钻孔走向及倾向瓦斯抽采半径,统计分析被保护层瓦斯抽采率,同时就地面群孔与井下底板巷穿层钻孔瓦斯抽采两种方法进行了抽采率、工程费用等方面的对比。研究结果表明：新集一矿的地层条件下地面钻孔抽采煤层卸压瓦斯沿煤层倾向和走向的抽采半径分别不小于160m和240m;采动区地面群孔瓦斯抽采率达35%以上;地面钻孔相对比井下底板巷,在抽采瓦斯方面具有技术上可靠、安全、经济等优点。     

高瓦斯特厚煤层煤与卸压瓦斯共采原理及实践

论述了高瓦斯低透气性有煤与瓦斯突出危险特厚煤层和上覆采动断裂带有高瓦斯涌出的特厚煤层两种煤与瓦斯高产高效卸压共采模式、原理及其实践所取得的丰硕成果。阐明了现场考察得出的煤层采动引起远程上覆煤层卸压变形规律与卸压瓦斯抽采规律。     

急倾斜煤层俯伪斜下保护层开采的卸压范围

以某煤矿急倾斜煤层俯伪斜下保护层开采为工程对象,采用有限元数值计算分析方法,从被保护层的应力和变形2个方面分析了保护层开采对被保护层的卸压程度和卸压保护范围;通过现场观测被保护层瓦斯动力参数变化,确定了被保护层实际的有效保护范围.2种方法得到的结果基本一致.结果表明:该矿井保护层开采后被保护层得到充分保护的倾向上部卸压角为90°、下部为82°,走向超前距离大于20 m,其被保护层卸压范围是一个近似椭圆型的卸压圈,卸压圈椭圆的中心区域是卸压效果最充分的区域,从卸压圈椭圆的中心到边界卸压效果逐渐减弱.     

煤与远程卸压瓦斯安全高效共采试验研究

运用高瓦斯煤层群煤与瓦斯安全高效共采的思想,在淮南潘一矿进行了煤与瓦斯安全高效共采及远程瓦斯抽采的试验研究：首先开采瓦斯含量低、无突出危险的B11煤层,利用其采动影响使处在其上部70m(相对层间距35)的C13煤层卸压,煤层透气性系数增加近3000倍,瓦斯大量解吸并形成了沿顺层张裂隙流动的条件,通过在C13煤层底板沿走向布置的瓦斯抽采巷向C13煤层均匀地打网格式上向穿层钻孔,C13煤层内的卸压解吸瓦斯在煤层残余瓦斯压力和抽采负压作用下沿顺层张裂隙向抽采钻孔汇集,瓦斯抽采率达60%以上,不仅消除了煤与瓦斯突出危险性,而且相对瓦斯涌出量由原来25m^3／t下降到5m^3／t,工作面日产量由原来的1700t提高到5100t,成功地实现了煤与瓦斯两种资源的安全高效共采。     

Principle and engineering application of pressure relief gas drainage in low permeability outburst coal seam

With the increase in mining depth, the danger of coal and gas outbursts increases. In order to drain coal gas effectively and to eliminate the risk of coal and gas outbursts, we used a specific number of penetration boreholes for draining of pressure relief gas. Based on the principle of overlying strata movement, deformation and pressure relief, a good effect of gas drainage was obtained. The practice in the Panyi coal mine has shown that, after mining the Cllcoal seam as the protective layer, the relative expansion deformation value of the protected layer C13 reached 2.63%, The permeability coefficient increased 2880 times, the gas drainage rate of the C13 coal seam increased to more than 60%, the amount of gas was reduced from 13.0 to 5.2 m3/t and the gas pressure declined from 4.4 to 0.4 MPa, which caused the danger the outbursts in the coal seams to be eliminated. The result was that we achieved a safe and highly efficient mining operation of the C 13 coal seam.     

近距离突出煤层群瓦斯治理技术优化的研究

近距离突出煤层群工作面受上下邻近煤层卸压瓦斯的影响,致使回采工作面瓦斯涌出量大、工作面回风隅角及回风巷中的甲烷传感器频繁报警,瓦斯治理消耗大量的人力、物力和时间,严重制约了矿井的安全生产。通过对几种瓦斯治理方案进行分析论证,得出将整个煤层群作为一个治理单元,统筹考虑,将煤层厚度、瓦斯含量相对较小的弱突出煤层作为关键保护层,配合打钻进行立体式抽采,实现上下递进保护,最大限度地抽采邻近煤层的卸压瓦斯的方案。现场实践结果表明,保护层工作面在回采期间瓦斯抽采率高达90%以上,回风隅角瓦斯浓度降至0.6%以下,回风巷风流中瓦斯浓度降至0.2%以下,工作面月平均回采长度由原来的120 m提高至200 m。同时,从根本上解决了被保护层工作面回采期间瓦斯带来的安全威胁。     

Fracture evolution and pressure relief gas drainage from distant protected coal seams under an extremely thick key stratum

When an extremely thick rock bed exists above a protected coal seam in the bending zone given the condition of a mining protective seam, this extremely thick rock bed controls the movement of the entire overlying stratum. This extremely thick rock bed, called a "main key stratum", will not subside nor break for a long time, causing lower fractures and bed separations not to close and gas can migrate to the bed separation areas along the fractures. These bed separations become gas enrichment areas. By analyzing the rule of fracture evolution and gas migration under the main key stratum after the deep protective coal seam has been mined, we propose a new gas drainage method which uses bore holes, drilled through rock and coal seams at great depths for draining pressure relief gas. In this method, the bores are located at a high level suction roadway (we can also drill them in the drilling field located high in an air gateway). Given the practice in the Halzi mine, the gas drainage rate can reach 73% in the middie coal group, with a gas drainage radius over 100 m.     

Key technologies and engineering practices for soft-rock protective seam mining

Severe gas disasters in deep mining areas are increasing, and traditional protective coal seam mining is facing significant challenges. This paper proposes an innovative technology using soft rock as the protective seam in the absence of an appropriate coal seam. Based on the geological engineering conditions of the new horizontal first mining area of Luling Coal Mine in Huaibei, China, the impacts of different mining parameters of the soft-rock protective seam on the pressure-relief effect of the protected coal seam were analyzed through numerical simulation. The unit stress of the protected coal seam, which was less than half of the primary rock stress, was used as the mining stress pressure-relief index. The optimized interlayer space was found to be 59 m for the first soft-rock working face, with a 2 m mining thickness and 105 m face length. The physicochemical characteristics of the orebody were analyzed, and a device selection framework for the soft-rock protective seam was developed. Optimal equipment for the working face was selected, including the fully-mechanized hydraulic support and coal cutter. A production technology that combined fully-mechanized and blasting-assisted soft-rock mining was developed. Engineering practices demonstrated that normal circulation operation can be achieved on the working face of the soft-rock protective seam, with an average advancement rate of 1.64 m/d. The maximum residual gas pressure and content, which were measured at the cut hole position of the protected coal seams (Nos. 8 and 9), decreased to 0.35 MPa and 4.87 m³/t, respectively. The results suggested that soft-rock protective seam mining can produce a significant gas-control effect.     

Reservoir reconstruction technologies for coalbed methane recovery in deep and multiple seams

Multiple coal seams widely develop in the deep Chinese coal-bearing strata. Ground in situ stress and coal seam gas pressure increase continuously with the increase of the mining depth, and coal and gas outburst disasters become increasingly severe. When the coal is very deep, the gas content and pressure will elevate and thus coal seams tends to outburst-prone seams. The safety and economics of exploited firstmined coal seams are tremendously restricted. Meanwhile, the multiple seams occurrence conditions resulted in different methane pressure systems in the coal-bearing strata, which made the reservoir reconstruction of coal difficult. Given the characteristics of low saturation, low permeability, strong anisotropy and soft coal of Chinese coal seams, a single hydraulic fracturing surface well for reservoir reconstruction to pre-drain the coalbed methane(CBM) of multiple seams concurrently under the different gas pressure systems has not yet gained any breakthroughs. Based on analyses of the main features of deep CBM reservoirs in China, current gas control methods and the existing challenges in deep and multiple seams, we proposed a new technology for deep CBM reservoir reconstruction to realize simultaneous high-efficiency coal mining and gas extraction. In particular, we determined the first-mined seam according to the principles of effectiveness and economics, and used hydraulic fracturing surface well to reconstruct the first-mined seam which enlarges the selection range of the first-mined seam. During the process of mining first-mined seam, adjacent coal seams could be reconstructed under the mining effect which promoted high-efficiency pressure relief gas extraction by using spatial and comprehensive gas drainage methods(combination of underground and ground CBM extraction methods). A typical integrated reservoir reconstruction technology, ‘‘One well for triple use", was detailed introduced and successfully applied in the Luling coal mine. The application showed that the proposed technology could effectively promote coal mining safety and simultaneously high-efficiency gas extraction.     

保护层开采卸压增透效应研究及其定量表征方法探索（研究生论坛稿件）

保护层开采是高突矿井瓦斯治理地主要方式及开采方法,保护层开采的卸压增透效果当前无法量化表征的,缺乏评价体系。以平板流体模型增透率理论为基础,结合平煤十矿地质条件,通过离散单元法建立保护层开采数值模型,获得保护层开采不同距离时采空区下方的增透率图谱及被保护层的应力分布。研究结果表明：保护层开采过程中,采面前方15 m处支撑压力会出现应力峰值,随着采面的推进,增透率与现场瓦斯流量呈现正相关关系;在采空区下方,被保护层卸压以及增透效应明显,且卸压区范围与增透率分布集中区域基本一致,均随着采空区范围的扩大而增大。该研究成果证实了增透率理论可以作为保护层开采卸压增透指标,对现场保护层回采设计、瓦斯抽采设计范围的确定提供了更加科学的依据。     

Effect of protective coal seam mining and gas extraction on gas transport in a coal seam

A gas–solid coupling model involving coal seam deformation,gas diffusion and seepage,gas adsorption and desorption was built to study the gas transport rule under the effect of protective coal seam mining.The research results indicate:(1) The depressurization effect changes the stress state of an overlying coal seam and causes its permeability to increase,thus gas in the protected coal seam will be desorbed and transported under the effect of a gas pressure gradient,which will cause a decrease in gas pressure.(2) Gas pressure can be further decreased by setting out gas extraction boreholes in the overlying coal seam,which can effectively reduce the coal and gas outburst risk.The research is of important engineering significance for studying the gas transport rule in protected coal seam and providing important reference for controlling coal and gas outbursts in deep mining in China.     

Similarity model tests of movement and deformation of coal-rock mass below stopes

For a study of the movement and deformation of coal-rock mass and low protected seams below a stope,as well as for fracture developments and rules of evolution of permeability,we designed a plane strain model test stand to carry out model tests of similar materials in order to improve the effect of gas drainage from low protected seams and to measure the movement and deformation of coal-rock mass using a method of non-contact close-range photogrammetry.Our results show that 1) using paraffin melting to take the place of coal seam mining can satisfy the mining conditions of a protective seam;2) coal-rock mass under goafs has an upward movement after the protective seam has been mined,causing floor heaving;3) low protected seams become swollen and deformed,providing a good pressure-relief effect and causing the coal-rock mass under both sides of coal pillars to become deformed by compression and 4) the evolution of permeability of low protected seams follows the way of initial values→a slight decrease→a great increase→stability→final decrease.Simultaneously,the coefficient of air permeability increased at a decreasing rate with an increase in interlayer spacing.     

朱仙庄煤矿Ⅱ831工作面区域条带消突技术研究

为了解决无保护层的煤层区域瓦斯治理的难点,分析了朱仙庄矿煤层及瓦斯赋存状况,提出了在不具备开采保护层的区域内,采用底板穿层钻孔区域防突措施,对掘进巷道进行打钻预抽。在详细介绍底板穿层钻孔的布置、抽采和计量方式的同时,通过理论计算和实际掘进作业两个方面,共同验证了底板穿层钻孔条带预抽区域措施可行性和可靠性,进而为穿层钻孔预抽区域措施在矿区的推广应用提供了范例。