技术经验薄煤层群煤与瓦斯共采技术研究舒彦民1，赵益2，孙建华2，姜天文2，张锦鹏2（1．龙煤集团七台河分公司，黑龙江七台河154600；2．黑龙江科技学院，黑龙江哈尔滨150027）摘要：七台河矿区具有煤层薄、透气性差、煤的坚固性系数小、瓦斯含量高、吸附性强、瓦斯涌出初速度衰减快等特点，同时矿区煤层群具有分组性，各组内煤层间距较小。
为解决煤层顺层钻孔施工难度大、瓦斯抽放效果差，以及回采工作面上隅角和回风流中瓦斯浓度容易超限等难题，提出沿空留巷邻近层瓦斯抽采技术，构建了七台河矿区薄煤层群煤与瓦斯共采技术体系，并在七台河桃山矿进行了应用研究。
应用结果表明，该技术能够实现煤与瓦斯安全高效共采。
关键词：煤与瓦斯共采；保护层开采；沿空留巷穿层钻孔；瓦斯抽采中图分类号：TD712+．67文献标志码：B文章编号：1008－4495（2011）04－0047－03收稿日期：2010－12－02；2011－03－25修订作者简介：舒彦民（1966—），男（满族），黑龙江阿城人，硕士，高级工程师。
七台河矿区位于黑龙江省东部，地处勃利煤田，煤炭资源赋存条件较差，向斜、背斜构造及断裂构造较多，煤层平均厚度0．86m ，是全国煤层最薄的矿区之一。
产品以焦煤、1/3焦煤和动力煤为主，是全国三大稀有保护性开采煤田之一。
目前，七台河矿区部分生产矿井的开采深度已达－500 －600m ，且开采深度、瓦斯含量和瓦斯涌出量每年以较高的速度递增，未来10年，煤与瓦斯突出威胁继续增大，深部开采面临巨大的技术挑战；另一方面，瓦斯（煤层气）既是我国煤矿生产过程中的主要灾害源，也是一种洁净能源和优质化工原料，是21世纪的重要接替能源之一。
针对七台河区煤层群的煤层薄、透气性差、煤的坚固性系数小、瓦斯含量高、吸附性强、瓦斯涌出初速度衰减快等特点，考虑到矿区煤层群具有分组性，各组内煤层间距小，存在邻近层和采空区瓦斯涌出量大，煤层顺层钻孔施工难度大、抽放效果差，回采工作面上隅角和回风流中瓦斯浓度容易超限等问题，提出煤与瓦斯共采技术新思路：煤层群进行分组开采，每组选取最佳首采关键层作为保护层进行开采，同时结合沿空留巷穿层钻孔抽采技术，对邻近层卸压瓦斯进行抽采，实现连续抽采卸压瓦斯与回采工作面采煤同步推进，实现高效的工业化煤与瓦斯共采，将抽采的高、低浓度瓦斯分别输送到地面加以利用。
1煤与瓦斯共采的基础理论煤与瓦斯共采是针对我国高瓦斯矿区煤系地层多为煤层群的条件和煤层的低透气性特征，将煤与瓦斯作为资源，结合我国煤矿长期治理瓦斯的成功经验，通过固、气2套系统进行煤与瓦斯安全高效共采的矿井瓦斯治理理念与方法，即通过“首采煤层”的开采，在煤系地层中产生“卸压增透增流”效应图，形成瓦斯“解吸—扩散—渗流”活化流动的条件，并通过合理高效的瓦斯抽采方法和抽采系统，同时实现瓦斯资源的高效抽采。
瓦斯资源的抽采可大幅度地减少“卸压煤层”的瓦斯含量，消除其煤与瓦斯突出危险性，减少卸压煤层开采时的瓦斯涌出量，从而实现卸压煤层的安全高效开采［1－2］。
1．1采空区顶板裂隙发育及瓦斯流动规律煤层开采将引起岩层移动与破断，并在岩层中形成采动裂隙。
按采动裂隙性质可分为2类：离层裂隙；竖向破断裂隙。
当采空区顶板充分垮落后，采空区中部岩层和下方的矸石紧密接触，从而使得采空区中部顶板岩层裂隙基本被压实，其四周形成一个环形的采动裂隙发育区，称之为“O ”形圈。
在“O ”形圈上方或者下方受采动影响的煤层瓦斯在含量梯度和压力梯度作用下以扩散和渗流的形式向“O ”形圈内运移，使得“O ”形圈成为卸压煤层瓦斯聚积和运移的主要通道［3－5］。
研究表明，在采空区竖直方向上，形成了一个“∩”形拱采动裂隙区。
采空区不同涌出源的瓦斯在浮力作用下沿采动裂隙带裂隙通道上升，上升中不断掺入周围气体，使涌出源瓦斯与环境气体的密度差逐·74·渐减小，直到密度差为0，混合气体则聚积在裂隙带上部的离层裂隙内。
涌入采空区的瓦斯，在其含量梯度作用下引起普通扩散，由于空气的重力作用产生方向向下的压强梯度，则其产生的扩散流方向，与压强梯度反向，即瓦斯气体具有向上扩散的趋势。
因此，在瓦斯浮力、含量梯度及通风负压的作用下，“∩”形拱采动裂隙区成为瓦斯聚积区，为采动裂隙带内钻孔抽采、巷道排放等治理瓦斯技术提供依据［3－6］。
1．2采空区底板裂隙发育及瓦斯流动规律在沿工作面推进方向，煤层底板岩层将出现压缩、膨胀、再压缩的过程。
在煤壁前方附近，煤层底板受支承压力的作用而被压缩，工作面推过后，底板处于膨胀状态，随着工作面的进一步推进，顶板岩层开始在采空区垮落，采空区内垮落矸石对膨胀底板又起着压实作用，并且随顶板垮落或顶板活动的结束施加给底板的压实荷载也越来越大，直至恢复或接近恢复到原岩应力状态。
上保护层开采后，采空区底板一定范围的煤岩层发生底鼓破坏和膨胀变形，结合采场底板岩层的裂隙发育状况，可将底板受到采动影响的煤岩层分为底鼓裂隙带和底鼓变形带，如图1所示。
根据现场试验考察及相关资料统计分析［7］，底鼓裂隙带下限在底板下方15 25m ，该带内的裂隙主要为煤岩层离层后形成的沿层理的顺层张裂隙和岩层破断后垂直、斜交层理形成的穿层裂隙，穿层裂隙将该带内的煤层与采空区导通，煤层瓦斯可沿穿层裂隙进入保护层采空区，瓦斯涌入采空区的阻力随深度的增加逐渐加大；底鼓变形带下限在底板下方50 60m ，该带内裂隙以沿层理形成的顺层张裂隙为主，处于该带的被保护层发生膨胀变形，吸附瓦斯解吸，大量卸压瓦斯汇集在煤层中的裂隙内，裂隙随层间距加大逐渐减少。
沿工作面走向，随着底板煤岩层应力的变化，可分为应力增高区、应力降低区和应力恢复区，如图2所示。
沿走向三区的划分，为下被保护层卸压瓦斯抽采最佳时间的确定提供了理论依据。
图1采空区底板裂隙分布及分带示意图图2下伏岩层裂隙发育及走向分区示意图2煤与瓦斯共采技术2．1煤与瓦斯共采技术体系由于七台河矿区煤层群具有分组性，各组内煤层间距较小，煤层开采受邻近层瓦斯涌出量影响较大，因此选择煤层群各组煤的中间煤层作为首采煤层，采用沿空留巷上向和下向穿层钻孔抽采首采煤层采空区和邻近煤层瓦斯，形成七台河矿区煤层群煤与瓦斯共采技术体系，实现首采层及其邻近煤层煤炭资源和瓦斯资源的安全高效开采。
七台河煤层群煤与瓦斯共采技术体系见图3。
图3七台河煤层群煤与瓦斯共采技术体系框图2．2沿空留巷穿层抽采技术根据七台河煤层群赋存地质特征、煤层实际开采情况及有效卸压范围计算可知，上保护层有效卸压范围小于50m ，下保护层有效卸压范围小于·84·100m ，因此在进行沿空留巷抽采邻近层卸压瓦斯时应选用中低位钻孔抽采采空区富集瓦斯技术。
在沿空留巷中设置抽采瓦斯管道，各倾向抽采瓦斯钻孔与抽采瓦斯管道连通，采空区上部及环形裂隙圈内的解吸游离瓦斯通过倾向抽采瓦斯钻孔，并通过抽采瓦斯管进入瓦斯抽采系统。
倾向抽采瓦斯钻孔布置的参数选取：终孔位置距采煤工作面回风巷的水平距离为10 30m ，距煤层顶板法向距离为采高的8 10倍，并且不小于30m ；倾角小于采动卸压角，缓倾斜煤层钻孔倾角不大于80ʎ，急倾斜煤层钻孔倾角不大于75ʎ；在中近距离保护层开采工作面，由留巷回风巷中施工的抽采瓦斯钻孔直接穿过上保护层，进行被保护层卸压瓦斯抽采。
留巷穿层钻孔抽采平面图见图4。
图4留巷穿层钻孔抽采平面示意图3应用与效果3．1矿井概况桃山煤矿位于七台河矿区西部生产区的东部，始建于1958年，原设计能力为75万t /a ，1983年经改扩建后设计生产能力为105万t /a ，2007年核定能力为117万t /a 。
42035采煤工作面位于三水平钢带机道左侧下部，为桃山煤矿三采区的第5个区段，工作面走向可采区域长度为900m ，倾向长度为150m ，平均煤层采高1．5m ，工作面煤层厚度比较稳定。
煤层走向115ʎ 145ʎ，倾向205ʎ 234ʎ，倾角22ʎ 26ʎ，平均24ʎ，采区边界处倾角较大。
煤层属比较稳定性煤层，结构复杂，西南倾向单斜构造，产状稳定，煤层变化不大。
开采煤层及邻近煤层结构如表1所示。
3．2抽采参数及效果采用留巷穿层钻孔抽采技术对42035采煤工作面采空区顶底板裂隙带进行瓦斯抽采，主要参数如下：穿层钻孔的终孔高度为14 20m ，倾角不大于75ʎ，施工时间在采煤工作面采后20m 以后，钻孔直径90mm ，钻孔成组设置，每组3个，钻孔偏向工作面60ʎ 70ʎ，抽采钻孔组间距20 25m ，孔口的封孔长度8m 。
表1煤层特征煤层煤层厚/m 距下分层垂距/m 结构顶板底板发育750 0．9036 450．6040简单粉砂岩粉砂岩全矿发育，南部不可采790．57 3．0030 601．5040复杂粉砂岩粉砂岩全矿发育830 0．700．50简单粉砂岩细砂岩全矿发育，北部由东向西，由浅入深变薄对42035采煤工作面采空区顶底板裂隙带进行瓦斯抽采后，上隅角瓦斯体积分数稳定在0．8%以下，且钻孔抽采瓦斯体积分数达54%以上，抽采量达48m 3/min 以上，解决了工作面上隅角和回风流瓦斯浓度超限问题，实现了煤与瓦斯共采目标。
4结语针对七台河矿区特点，为解决煤层顺层钻孔施工难度大、抽放效果差，回采工作面上隅角和回风流中瓦斯浓度容易超限等难题，提出了沿空留巷邻近层瓦斯抽采、顶板高位钻孔瓦斯抽采技术，构建了七台河矿区近距离薄煤层群煤与瓦斯共采技术体系，并在七台河桃山煤矿进行了应用研究，结果表明：桃山煤矿42035采煤工作面沿空留巷穿层钻孔瓦斯抽采技术治理瓦斯的效果明显，上隅角瓦斯体积分数稳定在0．8%以下，且钻孔抽采瓦斯体积分数达54%以上，抽采量达48m 3/min 以上，可以实现七台河矿区其他类似矿井的煤与瓦斯安全高效共采。
参考文献：［1］程远平，俞启香，袁亮，等．煤与远程卸压瓦斯安全高效共采试验研究［J ］．中国矿业大学学报，2004，33（2）：132－136．［2］俞启香．矿井瓦斯防治［M ］．徐州：中国矿业大学出版社，1992．［3］吴财芳，曾勇，秦勇．煤与瓦斯共采技术的研究现状及其应用发展［J ］．中国矿业大学学报，2004，33（2）：137－140．［4］谢生荣，武华太，赵耀江，等．高瓦斯煤层群“煤与瓦斯共采”技术研究［J ］．采矿与安全工程学报，2009，26（2）：173－178．［5］袁亮．留巷钻孔法煤与瓦斯共采技术［J ］．煤炭学报，2008，33（8）：898－902．［6］赵耀江，郭海东，袁胜军．综采面顶板走向大直径长钻孔瓦斯抽采技术参数的研究［J ］．太原理工大学学报，2009，40（1）：74－77．［7］于不凡．煤矿瓦斯灾害防治及利用技术手册［K ］．北京：煤炭工业出版社，2005．（责任编辑：李琴）·94·Vol．38No．42011MINING SAFETY&ENVIRONMENTAL PROTECTION Aug.2011English Abstracts of This IssueResearch on Oxygen-containing Liquefaction Technology for Low-concentration Coal-bed Gas in Coal Mining Area(1)－This paper gave a description of the present research situation of oxygen-containing liquefaction technology for low-concentration coal-bed gas both at home and abroad,expounded the technical scheme,safety measures and so on,the performance assessment of 4800m3/d oxygen-containing liquefaction pilot plant for low-concentration coal-bed gas was conducted,and the desired goal was fully achieved.Numerical Simulation Study on Thermal Environment in a Blind Heading with Combined Local Ventilation(3)－Based on k-εturbulence model,the distributions of the velocity field, streamline,temperature field,PMV-PPD(Predicted Mean Vote–Predicted Percentage Dissatisfied),mean age of air in a heading face with combined local ventilation in Zhouyuanshan Coal Mine were simulated by using Airpark2.1software.The results showed that the air duct layout and the air quantity distribution of the exhaust and forcing ventilation were reasonable,the air velocity was0.15≤v≤4.0m/s and the temperature t≤26℃when the large roadway cross section was S=12m2,the distance of the exhaust-duct and forcing-duct outlet to the heading face was L exhaust=16m and L forcing=8m respectively,and the air quantity ratio of exhaust ventilation to forcing ventilation with forcing air duct before the exhaust one was2:1.Numerical prediction and evaluation were conducted on the thermal environment by using the thermal comfort index-PMV-PPD and air quality index-air age.The numerical results and field investigation had a good consistence. Test Study on Unpowered Automatic Adding Device for Dust-fall Agent(8)－In this paper,the structure and working principle of the unpowered automatic adding device for dust-fall agent were described,and through the experimental study,the relation among the over-water pressure,over-water flow,adding medium,the length of suction tube and the adding precision was obtained.The site application showed that this device had the features of high adding precision,corrosion resistance,safety,reliability,easy installation and operation and so on,and can completely meet the underground use for the additon of chemical dust-suppression agent.Numerical Simulation on Influence of Cyclic Mine Air Curtain Outlet Velocity on Effectiveness of Obstructing Airflow(18)－A mathematical model of airflow field was established according to the characteristics of the air curtain obstructing airflow in mine roadway.The numerical simulation was conducted on the pressure field and velocity field at different air velocity with CFD software FLUENT,and its result was consistent with the theoretical data.The simulation results indicated that the airflow field might be divided into the stable upstream zone and downstream zone and the varying air-return zone according to the gradient of the static pressure and velocity so as to provide the basis for date measurement.The effective pressure decreased with the decrease of the air velocity at the air curtain outlet,which may cause the air leakage to be further increased,so when designing the air curtain, the obstructing capacity must match the obstructing pressure difference.Study on Distribution Law of Stress Field in Heading Face of Extra-soft Coal Seam with High Strata Stress(21)－With the increase of mining depth,the stress field in mining faces changes from shallow to deep part,obvious change occurred in distribution regularity of the prediction index for the heading face in bulky seam under the condition of high strata stress,so the urgent need is to understand the distribution regularity of the stress field in the heading face in extra-soft seam with high strata stress.The distribution regularity of the stress field in front of the heading face in the extra-soft seam with high strata stress was obtained with a combined method of theoretical analysis,field survey and numerical analysis.Test research was made on the sensitive index and critical value for outburst prediction in the heading face in the extra-soft seam with high strata stress and high gas pressure in Xinzhuangzi Mine in Huainan Coal Mining area.Study on Technical Mechanism and Application of“Five-step”Gradual and Fast Exposing Coal Seam in a Cross-cut (24)－The traditional technology for exposing outburst coal seams in a crosscut may come across some difficult problems such as that the blasting vibration is easy to induce outburst,the outburst treatment requires a lot of funds,and exposing outburst coal seams in the crosscut may seriously affect the safe production and economical benefits of the mine,for this purpose,a new technology of“five-step”gradual and fast exposing outburst coal seams in the crosscut was put forward.In this paper,study was made on the technical principle of the gradual and fast exposing outburst seams in the crosscut,and it came to the conclusion that the multi-parameter prediction was the technical key of gradual and fast exposing outburst seams in the crosscut;through tests,the multi-parameter prediction criteria for the coal seam outburst hazard in Songzao Coal Mining Area and the stereoscopic multiple layout of prediction holes were determined;study was made on the principle of establishing movable safe buffer zone for exposing outburst seams in the crosscut,and then the scope of the movable safe buffer zone was determined;with the shield of the safe buffer, outburst seams were exposed by shallow drivage and shallow advance,and finally,a complete set of new technology for gradual and fast exposing outburst seam in the crosscut was worked out. The site application in six mines in this coal mining area showed that this technology was simple,economic,rational,and safety in production,the time required for exposing outburst seams was reduced form110~257days to7~25days,the time for exposing outburst seam was greatly shortened.Network System of Coal Mine Gas Monitoring—Real-time Transmission of Dynamic Data(42)－The software for the real-time transmission of mine gas monitoring data was developed by taking VC++6.0as the programming platform,using Microsoft SQL Server2005database for storing data and on the basis of TCP/IP network transmission protocol.This paper described the framework design of the network system and discussed the real-time transmission of dynamic gas data,this thus provided real-time and accurate mine gas monitoring data for the exploration of Web page,and the remote monitoring management of coal mine’s management department to the mine was finally achieved. Research on Simultaneous Extraction Technology for Coal and Gas of Thin Seam Group(47)－Qitaihe Mining Area is characteristics of thin coal seams,low permeability for gas,low hardness coefficient of coal,high gas content,strong adsorbability and quick attenuation of the initial velocity of gas emission.In addition,the coal seams in this mining area have the character of subgroups and the interval between each group of seams is small. In this paper,the gob-side entry retaining for gas extraction from adjacent seams was put forward and the system for simultaneous extraction of coal and gas of thin seams in Qitaihe Mining Area was built in order to solve the difficult technical problems including the difficult drilling construction along seams,the poor gas drainage effect,and the disallowed gas concentration at the upper corner angle of the working face and in the return air.The application research on this technology was conducted in Taoshan Mine in this mining area.The extraction results indicated that the use of this technology could achieve the high-efficiency simultaneous extraction of coal and gas.Analysis of Subsided Column Development Characteristics in Kailuan Fangezhuang Mine(61)－The subsided column,as a special geological structure in north Chine coal field,has become a serious threat to mine safety.In this paper,the development law of the subsided column was obtained by the collection of the mine data and geological exploration data in Fangezhuang Mine and the observation analysis of the found subsided columns,and the formation mechanism of the subsided column was discussed.It was found out that the subsided column presented the law of north-west zonal distribution and in groups under the control of the general axial direction as the north-east Kaiping syncline structure,and it was mainly subjected to the control of Ordovician limestone,the structure development and the strong groundwater run-off.Discussion on Environmental Pollution-free Management Measures for Asbestos Waste(83)－The asbestos tailings and the abandoned asbestos products are classified as a kind of special hazardous waste for independent management in many countries and regions due to its huge amount,complicated types and high potential healthy and environmental risk.This paper summarized the generation situation of asbestos waste and the problems present in environment management in our country, described the advanced experiences of asbestos waste and environmental management in some developed countries and regions such as Japan and some EU countries,and put forward relevant environmental management suggestions for promoting the pollution-free management of asbestos waste in our country.。