高瓦斯低透气性煤层水力冲孔卸压增透技术研究

发布时间：2018-05-20 02:36

本文选题：水射流 + 水力冲孔　；参考：《中国矿业大学》2017年硕士论文

【摘要】：煤与瓦斯突出是影响煤矿安全生产最严重的灾害之一,随着开采深度的增加,煤层巷道掘进过程中突出危害越来越严重,传统的防突措施已不能满足矿井安全生产需要,因此,本文提出采用水力冲孔技术消除地应力和排放瓦斯的防突思想,主要研究内容包括以下几个方面:1.建立煤层巷道煤与瓦斯突出受力模型,分析了影响突出的因素;依据Mohr-Coulomb屈服准则,分析了卸压区煤体的稳定性,并且提出释放煤体应力和排放瓦斯是扩大煤体卸压区宽度、消除煤体突出危险性的有效途径。而后分析了卸压后的瓦斯从解吸到逸出到割缝缝槽中的过程,即采取了“解吸—扩散—渗流”的方式进入缝槽。2.从水力冲孔技术及增透机理出发,首先分析了水力冲孔水射流的主要特征。之后对水力冲孔技术破煤机理进行研究,依据动量定理,推导出水射流对煤体表面的总打击力公式,同时总结出水射流打击力与靶距和射流基本参数间的经验方程。最后根据以往实验结果对射流的最大冲击力离喷嘴出口距离进行了分析。3.分析研究喷嘴类型和参数对射流特性的影响,对水力冲孔喷嘴结构和参数进行选型计算,并对水力冲孔喷头体结构图进行了设计。而后对喷嘴出口水射流压力及水力冲孔破煤压力进行了计算,最后确定喷嘴的结构尺寸。4.利用FLUENT软件对水力冲孔喷头体的内部流场进行数值模拟,并采用FLAC3D软件对水力冲孔后的卸压效果进行模拟。水力冲孔的扩孔增透作用主要体现在:首先,冲出大量煤体,为煤体膨胀变形提供了充分的空间,使地应力向四周扩散,起到局部卸压作用。其次,在冲出煤体的过程中排出大量瓦斯,由于煤体的膨胀变形,煤层的透气性增加,扩大了瓦斯抽采影响半径,达到理想的抽采效果。最后,冲孔扩孔还增加了煤体裸露表面积,孔洞周围形成大量裂隙,增加单位时间抽采量,缩短预抽时间。5.在大平矿工作面进行水力冲孔技术现场试验,并观察水力冲孔后出煤量和排放瓦斯的防突效果。冲孔完成后,孔洞周围一定范围内煤体应力得到释放,瓦斯排放效果显著;工作面前方煤体产生位移,集中应力向深部转移,突出危险性得到降低或消除。综述所述:水力冲孔技术作为一种有效的防突措施,通过释放煤体应力和排放瓦斯,对煤体进行有效卸压,较明显的起到了防止煤与瓦斯突出的作用。
[Abstract]:Coal and gas outburst is one of the most serious disasters affecting the safety of coal mine production. With the increase of mining depth, the outburst hazards in the coal roadway excavation process become more and more serious. The traditional anti-outburst measures can no longer meet the needs of mine safety production. In this paper, the idea of using hydraulic punching technology to eliminate stress and gas outburst is put forward. The main research contents are as follows: 1. The stress model of coal and gas outburst in coal roadway is established, and the factors influencing outburst are analyzed. According to the Mohr-Coulomb yield criterion, the stability of coal body in pressure relief area is analyzed, and it is proposed that releasing coal body stress and discharging gas is to enlarge the width of pressure relief zone of coal body. The effective way to eliminate the danger of coal outburst. Then the process of gas desorption from desorption to escape to slit slot is analyzed, that is to say, the "desorption, diffusion-seepage" method is adopted to enter the slot. 2. Based on hydraulic punching technology and antireflection mechanism, the main characteristics of hydraulic punching water jet are analyzed. Based on the momentum theorem, the formula of the total impact force of water jet on coal surface is derived, and the empirical equation between the impact force of water jet and the target distance and the basic parameters of jet is summarized. Finally, the distance from the nozzle outlet of the maximum impact force of the jet was analyzed based on the previous experimental results. The influence of nozzle types and parameters on jet characteristics is analyzed. The structure and parameters of hydraulic punching nozzle are selected and calculated, and the structure diagram of hydraulic punching nozzle is designed. The water jet pressure at the nozzle outlet and the coal breaking pressure at the hydraulic punching hole were calculated, and the structure size of the nozzle was determined. The internal flow field of hydraulic punching nozzle was simulated by FLUENT software, and the pressure relief effect after hydraulic punching was simulated by FLAC3D software. The anti-reflection effect of hydraulic punching is mainly reflected in: firstly, a large number of coal bodies are flushed out, which provides a sufficient space for the expansion and deformation of coal bodies, and makes the in-situ stress spread around the area, which plays a role of local pressure relief. Secondly, a large amount of gas is discharged in the process of flushing out of the coal body. Because of the expansion and deformation of the coal body, the permeability of coal seam increases, which expands the influence radius of gas extraction and achieves the ideal extraction effect. Finally, punching and expanding holes also increase the exposed surface area of coal body, form a large number of cracks around the holes, increase the amount of extraction per unit time, and shorten the pre-extraction time of .5. Field test of hydraulic punching technology was carried out in Daping face, and the effect of coal production and gas outburst prevention after hydraulic punching was observed. After punching, the stress of coal body is released in a certain range around the hole, the effect of gas discharge is remarkable; the coal body in front of the face produces displacement, the concentration stress transfers to the deep, and the danger of outburst is reduced or eliminated. As an effective anti-outburst measure, hydraulic punching technology can effectively relieve the pressure of coal body by releasing coal body stress and discharging gas, which plays an obvious role in preventing coal and gas outburst.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD713.3

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