谢一矿开采上保护层卸压瓦斯抽采规律数值模拟研究

发布时间：2018-06-18 01:13

  本文选题：缓倾斜多煤岩层 + 上保护层　； 参考：《中国矿业大学》2017年硕士论文

【摘要】：钻孔或保护层采动卸压过程中煤岩体裂隙的产生和演化过程是其损伤的发展和累积过程,而瓦斯在损伤煤岩体中的流动过程是一个瓦斯运移与煤层变形之间相互耦合的复杂过程。本文根据岩体力学、损伤力学、流体力学等理论,进一步完善考虑损伤的Terzaghi有效应力,推导以应变为内变量的损伤演化方程和弹塑性损伤本构方程,确立煤体渗透率方程;结合解吸-渗流-扩散力学,建立考虑损伤的渗流-应力-损伤的含瓦斯煤岩固气动态耦合模型,对实验区C13煤层底板岩巷穿层钻孔抽采瓦斯规律进行研究和理论分析,并与现场工程对比分析,以验证数值分析的可行性。综上所述,本文主要的研究结论如下:分析谢一矿望峰岗井突出危险性和瓦斯地质规律等相关资料,结合矿区煤层特征,谢一矿具备优越的保护层开懫条件,同时进行C13煤层的卸压瓦斯抽采,可以从根本上改变谢一矿瓦斯治理的被动局面。采用宏观和微观分析相结合的方法得出淮南煤与瓦斯突出煤层(分层)煤样具有孔隙结构曲线呈双“S”形、吸附常数b0.5MPa-1的孔隙结构特征。通过模型分析:开采保护层,在采空区顶(底)板一定范围的煤岩层内形成的卸压区,在工作面前方和开切眼外侧形成应力集中。随着工作面的继续推进,卸压保护范围增大,卸压区底鼓量增大,同时被保护煤层工作面前方应力集中区向前移动。工作面推进超过100m后,被保护层膨胀带内的最大膨胀率达到3.2‰,膨胀带长期保持并逐渐向回采工作面位置转移,同时,压实区压缩率也逐渐达到1.3‰。随着抽放时间的持续,抽采瓦斯的影响范围逐渐扩大,钻孔周围瓦斯压力逐渐降低,瓦斯进一步解吸,煤层等效应力减小,煤层被压实,其透气性亦逐渐减弱,钻孔抽采速率逐渐减小,最终趋于稳定。抽采150天后,瓦斯的抽采速率接近27L/min,有效抽采半径近2m。现场工程表明:随着保护层工作面的向前推进,测定卸压区C13煤层开始最大相对膨胀变形为4‰;-780m C13南北底板岩巷穿层钻孔抽采瓦斯南段,单孔平均流量逐渐增大,最大值为22.0156L/min后逐渐衰减。北段单孔平均流量1.157~2.083 L/min。
[Abstract]:The formation and evolution of fractures in coal and rock mass during the mining and unloading process of borehole or protective layer is the development and accumulation process of its damage. The flow process of gas in damaged coal and rock mass is a complicated process of coupling between gas migration and coal seam deformation. Based on the theories of rock mechanics, damage mechanics and fluid mechanics, the effective stress of Terzaghi considering damage is further improved, and the damage evolution equation and elastic-plastic damage constitutive equation are derived, and the permeability equation of coal body is established. Combined with the mechanics of desorption, percolation and diffusion, the dynamic coupling model of gas-bearing coal and rock with seepage, stress-damage and damage is established, and the law of gas extraction through boreholes in rock roadway of floor of coal seam C13 in experimental area is studied and analyzed theoretically. In order to verify the feasibility of numerical analysis, it is compared with field engineering. To sum up, the main research conclusions of this paper are as follows: analyzing the relevant data, such as outburst risk and gas geological law of Wangfenggang well in Xieyi Mine, combining with the coal seam characteristics of mining area, Xie I Mine has superior conditions for opening protective layer. At the same time, the passive situation of gas control in Xieyi Coal Mine can be fundamentally changed by discharging pressure gas from coal seam C13. By combining macro and micro analysis, it is concluded that the coal samples in Huainan coal and gas outburst coal seam (stratified) have double "S" shape pore structure curve and adsorption constant b0.5MPa-1. Through model analysis: the stress concentration is formed in the pressure relief area formed in a certain range of coal and rock strata of the top (bottom) plate of the goaf and in the front of the face and the outside of the opening hole. As the working face continues to advance, the pressure relief protection range increases, the pressure relief area increases, and the stress concentration area in front of the protected coal face moves forward. The maximum expansion rate of the protected layer in the expansion zone is 3.2 鈥，

本文编号：2033319