大型三维模拟条件下大采高综采覆岩卸压瓦斯运移机理实验研究

The root cause of gas overrun in coal mining face and upper corner of fully mechanized coal seam with large mining height is the emission gas which come from goaf, and it is the basic way to study the gas migration in the fracture of the overlying strata and then obtained the gas enrichment area.Based on this academic thought of “fractures provide gas storage and transportation channels - gas enrichment caused by migration”,according to the characteristics of large mining height of the mining height is large, the fissure space is large, and the fractures are rich.And studied on gas migration mechanism by large scale three-dimensional experimental.Established the mathematical model of coal rock fracture -gas migration,then derived the gas solid similarity criterion which is suit for large scale three-dimensional experiments,basis on this a new physical similarity material is made. based on the physical simulation method,obtained the evolution characteristics of fractures and the distribution of porosity in the overburden under the condition of large mining height.The model is ventilated by U/ U+L/Y type,obtained the distribution of gas concentration, pressure and flow in the fracture of overlying strata,and its three dimensional spatial distribution, which is combined time-space effect.To further reveal the mechanism of gas migration and to establish the discriminant model of the main controlling factors of gas migration in the fracture of fully mechanized coal mining.Verify the reliability of the results by Using the COMSOL Multiphysics software and field industrial test,to provide a theoretical basis for coal and gas safety mining.

大采高综采工作面、上隅角瓦斯超限的根本原因是采空区瓦斯的涌出，而研究覆岩裂隙中瓦斯运移进而得到裂隙瓦斯富集区域是进行采空区瓦斯治理的根本途径。基于“裂隙提供瓦斯储运通道-运移造成瓦斯富集”这一学术思路，针对大采高综采采高大、裂隙空间大、覆岩裂隙发育丰富的特征，对瓦斯运移机理进行了大型三维实验研究。建立了煤岩破断-瓦斯运移数学模型，进而推导适合大型三维实验的气-固相似准则，以此为理论基础配置新型物理相似材料，以物理模拟的方法得到大采高条件下覆岩裂隙演化特征、空隙率分布特征，分析瓦斯最优运移通道；对模型进行U、U+L、Y型通风，结合时空效应得到覆岩裂隙中瓦斯的浓度、压力、流量分布及其三维空间分布云图，进一步揭示瓦斯运移机理并构建大采高综采覆岩裂隙中瓦斯运移主控因素判别模型；采用COMSOL Multiphysics软件以及现场工业试验对研究结果的可靠性进行验证，为煤与瓦斯安全共采提供理论依据。

大采高综采煤层推进速度快瓦斯涌出量大，卸压瓦斯抽采能够有效的降低工作面及上隅角瓦斯浓度保障煤矿安全生产，卸压瓦斯抽采的关键在于卸压瓦斯运移理论找到瓦斯富集区域。项目采用理论分析、物理相似模拟实验及数值模拟等多种手段相结合的方式，对大采高综采覆岩卸压瓦斯运移机理开展研究。基于采动裂隙场与卸压瓦斯渗流场的数学模型，推导出煤岩破断-瓦斯渗流固气耦合数学模型，进而得到固气耦合的相似条件。利用自主研制的大型三维物理相似模拟实验系统开展了物理模拟实验，通过声发射监测与微型内窥镜窥测以及大型三维模型剖切相结合的方法，得到大采高综采条件下覆岩破断及裂隙发育特征。基于采场推进动态发展演化的空间结构以及裂隙场发育、扩展全面测定的研究，研究了U型、U+L型通风方式下采场裂隙空间中瓦斯分布规律；最后通过分析大采高综采条件下瓦斯运移的控制因素，得到了大采高综采条件下卸压瓦斯运移机理。项目研究结果能够有效指导矿井卸压瓦斯抽采，有效提高瓦斯抽采效率，对工作面及采空区瓦斯治理具有重要的意义。