【作者】 张嘉勇；

【导师】 罗新荣；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2011， 博士

【摘要】 煤与瓦斯突出是严重威胁煤矿安全生产的灾害事故，不仅给国家和人民生命财产造成重大损失，而且严重制约了突出煤层的掘进速度，影响矿井采掘接替计划，制约煤矿安全高效生产。通过对煤与瓦斯突出的影响因素、煤与瓦斯突出机理和目前防治突出措施的综合分析，提出了高压小射流掏槽防突机理：煤体瓦斯释放，瓦斯压力梯度降低；应力集中带前移，应力梯度降低；煤体收缩变形，强度增加。研制了高压小射流防突装置及其配套设施：液压控制系统、远程监控系统和掏槽系统，通过实验室加压试验和行走实验，提高了装置的可靠性。制定了高压小射流防突技术工艺和安全防护措施，降低灾害事故的发生几率，加快突出煤层掘进速度，缓解突出煤层采掘接替紧张的局面。运用ANSYS有限元分析软件，对高压小射流冲击煤体破碎效果和巷道围岩变形数值模拟分析，验证了高压小射流在煤体掏槽过程中，促使冲孔内煤体暴露面积的增加，为深部煤体泄压和瓦斯渗流提供有利条件。同时槽孔周边一定区域的煤体发生变形移动，促进煤体内部裂隙的发育，增大煤层的透气性，扩大了槽孔周边煤层瓦斯的释放范围；另外高压小射流动力作用下，槽孔孔壁煤体产生较大的膨胀变形，促进裂隙的沟通和发育，增加了深部煤体瓦斯释放几率；冲孔区域煤体的破碎和变形，促使集中应力向煤层深部转移，煤体受力降低，煤体弹性能释放，裂隙充分发育，大量吸附状态的瓦斯演变为游离状态的瓦斯，经沟通裂隙充分释放，降低了突出煤层瓦斯压力梯度，消除了突出的危险性。综合分析不同巷道模型掏槽后的围岩应力和煤体位移变化情况，确定了高压小射流掏槽位置应距离巷道底板2/7处左右，掏槽孔径的大小为巷道底板长度的4/15左右，这样巷道围岩裂隙发育充分，且保持了围岩的完整性，有利于加快工作面的掘进速度。高压小射流冲孔试验表明在相同压力和流量下，同强度试样中冲出相同孔径的时间随着流量的增加而减小。当射流压力超过试样强度极限时，增大流量更有利提高射流的扩孔效果，因为在保持射流压力一定的情况下，提高枪嘴的射流流量，水流的搬运能力增强，促使更多孔底残留的煤块排出孔外，提高了冲孔速度。冲孔后试样加压试验表明试样冲孔孔径的增加，试样的抗压强度越来越小，试样强度损失比呈增大趋势，这表明大孔径对试样的泄压效果明显。而强度较大的试样在相同的冲孔孔径下，试样的破坏时间较长，强度损失比较小，因此，强度较大试样中需增大孔径才能达到较好的泄压效果。确定了高压小射流掏槽施工工艺，为设备现场应用提供技术支持。制定了掘进施工的安全防护措施，人员在距离施工端头200~300m的临时避难所内操作控制柜的流量阀门，控制液压马达进行往复运动，驱动高压水枪进行掏槽。对小射流掏槽废水进行净化处理，实现循环利用，同时对掏槽过程中释放的瓦斯进行集中抽放，收集作为一种能源，利废为宝，其经济和社会效益将会十分显著。更多还原

【Abstract】 The coal and gas outburst threatened safety production of mines, not only causedheavy losses of life and property, but also restricted driving speed of the prominent seamsseverely, which impacted mining and play of preparation and wining work, andconstrained safety and efficient production of coal mines.Through comprehensive analysis of influence factors, outburst mechanism andcurrent control measures, this paper proposed outburst prevention mechanism ofhigh-pressure small jet cutting: coal gas release, gas pressure gradient decrease; stressconcentration zone move forward, stress gradient reduce; coal shrinkage deform andstrength increase. Develop high-pressure small jet equipment and facilities: hydrauliccontrol system, remote monitoring system, cutting system. Pressure laboratory testimproved sealing device and pressure resistance. High-pressure small jet technology andsecurity measures against outburst was developed, which would reduce disasteroccurrence, speed up cutting rate and eases tension of preparation and wining work.Using ANSYS finite element analysis software, the crushing effect and wall rockdeformation of a small high-pressure jet impacting coal were given numerical simulationanalysis. It verified that impacting increased exposed area of coal in punch, providingconditions for pressure relief of internal coal seam and gas seepage. At the same time,coal around slot in a certain area moved and deformed to develop cracks of internal coal,which increased the permeability of coal seams and expanded gas release range; Also asdynamic action of a small high-pressure jet, slot wall coal expanseded greatly and cracksbecame more favor to gas release of deep coal; Cracks and deformation madeconcentration stress transfer to deep coal seams, thus force on coal reduced and elasticenergy released, then cracks developed fully, a large number of gas on adsorption statebecame free and released fully through cracks, which reduced gas pressure gradient ofcoal seams and eliminated outburst risk. Through comprehensive analysis of the rockstress and coal displacement of different roadway models after undercutting, it wasdetermined that undercutting should be2/7or so from tunnel floor, aperture size was4/15or so of roadway floor length, thus roadway fissures developed full, and maintainedrock integrity, in favor of speeding up the face driving.Punching tests showed that punching same diameter was fast as flow increased onthe same pressure and flow rate of the same strength samples. When jet pressureexceeded sample ultimate strength, increasing flow was more favor to punching effect. This was because that increasing jet flow improved water handling capacity, which mademore remain coal on hole bottom discharged and enhanced punching speed. Increasingpressure after punching tests showed that punching diameter increased, compressivestrength of samples decreased and strength loss was on increasing trend, which verifiedthat large diameter relief effect was obvious. Larger intensity samples with the samepunching diameter holes were destructed difficultly and strength loss was small. Solarger intensity samples needed to increase diameter to relief pressure effectly.Construction process of high-pressure small jet cutting provided technical supportfor on-site applications. Security measures of excavation construction developed,personnel in temporary shelters at a distance of200~300m construction ends operatedthe flow valve of control cabinet, and controled hydraulic motor to reciprocating motionand drived high-pressure water gun to undercutting. Cutting wastewater was purified toachieve recycling. Cutting gas was used as a source of energy. So its economic and socialbenefits would be very significant.更多还原