Mechanism of gas pressure action during the initial failure of coal containing gas and its application for an outburst inoculation

Faced with the continuous occurrence of coal and gas outburst(hereinafter referred to as“outburst”)disasters,as a main controlling factor in the evolution process of an outburst,for gas pressure,it is still unclear about the phased characteristics of the coupling process with in situ stress,which induce coal damage and instability.Therefore,in the work based on the mining stress paths induced by typical outburst accidents,the gradual and sudden change of three-dimensional stress is taken as the background for the mechanical reconstruction of the disaster process.Then the true triaxial physical experiments are conducted on the damage and instability of coal containing gas under multiple stress paths.Finally,the response characterization between coal damage and gas pressure has been clarified,revealing the mechanism of action of gas pressure during the initial failure of coals.And the main controlling mechanism during the outburst process is elucidated in the coupling process of in situ stress with gas pressure.The results show that during the process of stress loading and unloading,the original gas pressure enters the processes of strengthening and weakening the action ability successively.And the strengthening effect continues to the period of large-scale destruction of coals.The mechanical process of gas pressure during the initial failure of coals can be divided into three stages:the enhancement of strengthening action ability,the decrease of strengthening action ability,and the weakening action ability.The entire process is implemented by changing the dominant action of in situ stress into the dominant action of gas pressure.The failure strength of coals is not only affected by its original mechanical strength,but also by the stress loading and unloading paths,showing a particularly significant effect.Three stages can be divided during outburst inoculation process.That is,firstly,the coals suffer from initial damage through the dominant action of in situ stress with synergy of gas pressure;secondly,the coals with spallation of structural division are generated through the dominant action of gas pressure with synergy of in situ stress,accompanied by further fragmentation;and finally,the fractured coals suffer from fragmentation and pulverization with the gas pressure action.Accordingly,the final broken coals are ejected out with the gas action,initiating an outburst.The research results can provide a new perspective for deepening the understanding of coal and gas outburst mechanism,laying a theoretical foundation for the innovation of outburst prevention and control technologies.

Effectiveness analysis of methane-drainage by deep-hole controlled pre-splitting blasting for preventing coal and gas outburst

In the study of the application effectiveness of deep-hole controlled pre-splittingblasting technology,it was found through laboratory micro test and field study on a mine insouth China that under the technology,coal masses produce many irreversible cracks.Afterblasting,the nearer the distance from blasting hole,the larger the BET surface areaand volume ratio of the infiltration pore are;they increased by 11.47%and 5.73%,respectively.The coefficient of air permeability is increased 4 times.After 3 months,the gasdrainage rate was increased by 66%.In the first 15 days,the cumulative pumped gas was1.93 times of blasting before.The average absolute gas emission decreased by 63.46%.Experimental results show that deep-hole controlled pre-splitting blasting not only preventscoal and gas outburst,but also gives good economic results.

Study on comprehensive gas control techniques and practice in coal mines

The origins and main control methods of gas in coal seams were introduced cursorily, and the processes that need to be done in controlling gas, which includes prediction of gas emissions, drainage systems, the means of prevention of gas outbursts, and some suggestions were put forward. The characteristic of different gas emissions and the corresponding counter measures were presented, and ＆ case study of simultaneous extraction of coal and gas in Xieyi Coal Mine was carried out by coal mining and gas extraction without coal-pillar. The field application shows that gas drainage ratio in panel 5121（0） averages about 90% and reaches as high as 95~/0, which will give beneficial references to gas control in coal mines.

Issues in the outburst prevention work of coal mines in Guizhou Province and the analysis of its countermeasures

In order to reduce the occurrence of coal and gas outburst accidents, and improve the capability to prevent gas hazards and realize the safe and efficient mining of coal enterprises. The distribution of the outburst coal mining area of Guizhou Province and the status of coal and gas outburst and the problems in the current outburst prevention methods were analyzed. The main issues were pointed out such as the lack of regional outburst prevention measures, unsatisfactory effect in drainage, poor management and implementation, as well as personnel that need more training. The prevention situation of coal and gas outburst in Guizhou Province was considered. In accordance with the above problems, from the perspective of strengthening geological exploration, testing coal seam parameters, studying outburst prevention technologies, deploying mining systems rationally, improving mine safety management systems, and strengthening protection facilities and other aspects, a targeted outburst prevention measure and proposals were put forward.

CONTROL OF GAS EMISSION AT COAL FACE IN CHINA

All the underground coal mines in China are gassy mines. The gas emission at coal face increasingly grows with the increase of working depth and coal output, for example, the gas emission at a full mechanized coal face of mine No. 2 at Yongquan with a daily output of 2. 000t/d is up to 66-72m2/min. Special gas emission phenomena such as gas blowout, gas and coal outburst etc. have occurred at some faces, which threatens the safe production of face. obstructs the growth of productivity and limits the full play of mechanized equipment.In this paper, gas at face is divided, according to its origin, into three constituents, namely , coming from the coal wall, mined coal and goaf;and a formula for calculation is given. Also , the characteristics of the variation of gas emission at coal face, and the influence of mining sequence of a group of seams and supplied air quantity on the gas emission are discussed. Furthermore . based on the regularity of gas emission at coal face from the above three sources, and on the experiences of years, three principles on controlling gas emission at coal face are presented, that are managing the gas on classification basis, harnessing each source separately and comprehensive prevention and control. Finally, technical measures for prevention and treatment of the accumulation of gas in the upper corner of face, at the working place of coal-winning machine and in the bottom trough of conveyor are introduced.

Near-source characteristics of two-phase gas-solid outbursts in roadways

Coal and gas outbursts compromise two-phase gas-solid mixtures as they propagate as shock waves and flows from their sources.Propagation is influenced by the form of the outburst,proximity to source,the structure and form of the transmitting roadways and the influence of obstacles.The following characterizes the propagation of coal and gas outbursts as two-phase gas-solid flows proximal to source where the coupled effects of pulverized coal and gas flows dominate behavior.The characteristics of shock wave propagation and attenuation were systematically examined for varied roadway geometries using experiments and numerical models.The results demonstrate that the geometry of roadway obstructions is significant and may result in partial compression and sometimes secondary overpressurization in blocked and small comer roadways leading to significant attenuation of outburst shock waves.The shock waves attenuate slowly in both straight and abruptly expanding roadways and more significantly in T-shaped roadways.The most significant attenuation appears in small angle comers and bifurcations in roadways with the largest attenuation occurring in blocked roadways.These results provide basic parameters for simplifying transport in complex roadway networks in the far-field,and guidance for the design of coal and gas outburst prevention facilities and emergency rescue.

贵平煤矿地质灾害研究及防治

随着煤矿开采的不断深入,所引起的地质灾害越发严重,特别是在开采多煤层时,地质灾害影响更为严重。为加强对山体滑坡、陡岩崩塌、泥石流、地面塌陷、地裂缝等地质灾害的防治,改善煤矿地质环境,根据矿井实际情况,结合各类地质灾害发生的特点,采取对采空区进行地表下沉量预测、无人机遥感监测等有效的防治措施,实现对风险的有效预防与控制,并加强地质灾害治理,保护煤矿地质生态环境,实现矿井长期安全稳定发展。

煤矿瓦斯治理及防突对策分析

瓦斯问题长期以来一直是威胁煤矿工人生命安全和煤矿稳定运营的主要隐患之一。瓦斯超限不仅会引发突出和爆炸等事故,还可能导致重大的人员伤亡和财产损失。综合分析了引发煤矿瓦斯问题的原因,评估了当前瓦斯治理技术的效果,并提出具有创新性的优化措施,以期为煤矿瓦斯治理提供更加全面和实用的解决方案。

基于定向水力掏煤的层内“保护层”强化抽采技术

为解决底抽巷穿层钻孔水力掏煤范围小、钻孔覆盖距离短、精准度差的问题,胡底煤业从本煤层极薄保护层定向水力掏煤防突机理分析出发,结合定向钻机无线测量技术及水力掏煤技术,在13091巷迎头钻场开展定向钻孔水力掏煤试验。实践表明,定向钻孔水力掏煤后钻孔抽采浓度和百米钻孔流量都有提升,同时缩短了抽采达标所需时间,实现了消突的目的。该项技术具有远距离、精准、全方位消突及经济效益好的特点,可以广泛应用于突出矿井的区域瓦斯治理。

Experimental research on methane control of mining upper protective layers

In order to solve coal and gas outbursts during mining coal seam,studying on related problems were carried out. According to the theories of mining upper protective layer,proper mining plan were designed and performed through field experiment. By means of examining several parameters obtained from the field experiment,the protective effects were evaluated and the protective scope and related parameters were determined. The results of field experiment show that the danger of outbursts was evidently eliminated and the method of mining protective layers is effective and the safety and economic benefits are remarkable. The research has really applied worth and will give beneficial references to mining area with analogous conditions.

桑树坪二号井难抽采煤层瓦斯突出特征与防治

为了实现煤与瓦斯突出矿井高效瓦斯治理,以桑树坪二号井3号难抽采煤层为背景,在分析煤矿地质条件研究的基础上,充分利用已有研究成果,通过对有关数据的梳理和分析总结了桑树坪煤矿主采3号煤层的瓦斯突出特征。在已有煤与瓦斯突出基础上,提出了相应的区域和局部防突措施,最后以4321工作面作为实验工作面,对瓦斯防突效果进行检验。结果表明,该煤层瓦斯的突出动态过程主要是由地应力引起的,突出程度较轻、无规律,采用区域和局部综合防突措施后,防突效果检验表明其钻屑体积指数很小,实现了难抽采煤层瓦斯突出的有效防治。

贵州瑞丰煤矿开采充水因素分析及涌水量预测

以瑞丰煤矿以往地质勘查资料为基础,结合现场调查,对瑞丰煤矿水文地质条件进行综合分析,查明充水水源及途径,得出瑞丰煤矿属岩溶裂隙充水矿床,区内地下水主要靠大气降水补给,充水通道主要以岩溶裂隙为主,其次为采空区巷道、岩石裂隙。并采用比拟法对矿区涌水量进行预测,结合充水因素分析以及顶、底板含水层突水计算,得出煤层开采主要受煤系上覆夜郎组玉龙山段和长兴组地层岩溶裂隙水影响,为煤层开采的主要威胁。此次研究成果为瑞丰煤矿下一步开采及防治水工作提供了可靠的水文地质依据。

复杂低渗高瓦斯煤层CO_(2)气相压裂强化增透技术研究

山西华晋吉宁煤业有限责任公司(吉宁煤矿)开采的山西组2号煤层为典型的复杂低渗难抽煤层,透气性系数为0.023m^(2)/(MPa2·d),瓦斯含量8~10.52m^(3)/t,存在“多分层,多夹矸,采前难抽,采中涌出大”的特点。为此,在吉宁煤矿2201掘进工作面开展185MPa高压力、大容量的CO_(2)气相压裂强化造缝、增透防突瓦斯治理技术,考察其瓦斯抽采和防突效果。结果表明:(1)CO_(2)气相压裂技术能有效提升裂孔瓦斯抽采效率,瓦斯抽采纯流量最大值为0.193m^(3)/min,平均值为0.138m^(3)/min。(2)与前期条带预抽防突技术措施相比,CO_(2)气相压裂技术实施后,煤层瓦斯抽采纯流量提高了4.6~9.7倍,瓦斯有效抽采时间缩短47天,月掘进速度由原来36m提高至80m,提高了2.22倍,瓦斯抽采成本降低为原来的50%。

水力冲孔技术在严重突出煤层中的应用

分析了掘进工作面各种防突措施的优缺点,研究了水力冲孔技术的防突机理,阐述了水力冲孔的工艺流程.研究表明,在严重突出矿井采用水力冲孔措施,可有效地消除激发突出的应力,大幅度地释放煤体中的瓦斯,增大了煤体抑制突出的阻力,很好地起到了综合防突的作用,且提高巷道掘进速度2～3倍.

煤巷掘进水力掏槽防治煤与瓦斯突出技术

通过理论研究和工业试验,确定了水力掏槽新掘进防突措施,并提出了适合焦作矿区的防突措施参数,系统评价了水力掏槽防突措施的有效性、适应性和安全性.研究结果表明:水力掏槽防突措施是高压水通过水枪产生高流量的稳定射流破碎前方煤体形成槽硐,槽硐周围煤体得到充分卸压,释放出大量瓦斯,煤体物理力学性质发生改变.当卸压槽具有足够面积时,在巷道周围形成卸压和排放瓦斯的煤带,解除突出危险性.2 000 m严重突出地区巷道掘进表明:正常掘进期间未发生一次突出,巷道安全掘进速度提高2倍以上.

煤与瓦斯突出过程中瓦斯作用的研究

为了对煤与瓦斯突出事故进行有效的预防与控制, 分别从孕育和突出两个阶段阐述了瓦斯在煤与瓦斯突出中所起的作用, 指出了煤层吸附瓦斯和裂隙瓦斯对煤的物理力学性质的影响;由于空隙瓦斯的存在, 加剧了煤体失稳破坏的过程; 特别指出突出的主要能源来自于瓦斯的膨胀能; 并根据这一结论提出了相应的防突措施.

抑制突出的增压揭煤法研究

根据突出机理的球壳失稳假说给出的 3个力学条件 ,提出了一种新的抑制突出的方法——增压揭煤法 .通过 1 0次增压揭煤试验及相应的对比试验 ,证明在增压揭煤的条件下可以显著地抑制煤层的突出危险性 ,为煤矿现场提供了一种快速。

我国煤与瓦斯突出防治理论技术研究进展与展望

我国是世界上煤与瓦斯突出灾害最为严重的国家,在突出预防方面进行了大量深入的研究和实践,突出防治取得了较为显著的效果,但近年来突出灾害事故仍时有发生。为了进一步提高深部矿井煤与瓦斯突出防控技术,提升煤矿安全、智能化水平和煤炭安全保障能力,分析了突出发生机理研究进展及现状,阐述了我国煤与瓦斯突出预测及监测预警手段的关键技术,系统总结了防治煤与瓦斯突出的措施及新兴技术。我国在煤与瓦斯突出机理、预测、监测和防治等理论与技术方面取得了系列创新性成果,解决了大量理论和技术难题。但是,随着我国煤矿开采深度的增加,煤矿突出危险性日趋严重复杂。与此同时,国家对煤矿安全生产的要求也越来越高。针对新形势下煤与瓦斯突出防治现状和需求,亟需建立更为适应完善的煤与瓦斯突出防治理论及技术体系。基于此,提出了未来发展趋势及研究展望:在突出机理方面,应加强复杂多变地层及不同构造条件下突出耦合演化机理和定量化表征研究;在突出危险性鉴定方面,需关注低参数突出多发背景下不同区域及类别突出危险性的适应性判定标准研究;在瓦斯参数测试方面,应聚焦精细化定点测量及随钻反演技术的发展;在工作面突出危险性精准探测/预测/监测预警技术方面,应加强物联网、大数据分析及人工智能识别技术在突出危险性综合监测、智能预警方面的研究与应用;在防治方面,应进一步发展煤层突出危险性远程、区域、智能防控技术;在风险隐患管控方面,应深入研究并推广瓦斯灾害风险大数据分析与预警平台,从而全面提高我国瓦斯灾害风险隐患管控能力和瓦斯治理水平。

贵州煤与瓦斯突出事故规律性研究

通过对贵州省2000年—2010年煤与瓦斯突出事故的统计分析,并结合贵州煤矿的地质特点,得出煤与瓦斯突出事故发生的主控因素主要包括3方面,分别是煤层瓦斯含量高,防治突出措施不到位,乡镇煤矿数量比例大。综合分析各因素之后,为贵州省预防煤与瓦斯突出提出了相应的对策和建议。

淮北煤田煤与瓦斯突出地质因素分析与防治

分析了影响淮北煤田煤与瓦斯突出的地质因素主要为区域构造、深度、围岩性质、断层、煤层厚度变化、煤层结构变化;提出了适合淮北地质条件的防突措施为地面钻孔预抽突出煤层瓦斯、开采保护层、钻孔超前卸压排放、石门多循环解突揭煤、突出煤层近距离岩巷掘进、立井揭煤等。