深部低渗透性突出煤层爆破动载下聚能切缝增透机理及应用研究

In the process of the rock cross-cut coal uncovering and drivage of the low permeability coal seams, coal seam permeability is low, the gas extraction is difficult, gas disasters are occured frequently. Thus in this project, cumulative blasting column will be designed to implement directional cutting coal and rock seam, which can increase the timeliness of the coal and rock unloading and increasing permeability. Gas extraction becomes efficient and rapid elimination outburst is realized in deep low permeability outburst coal seams. On the basis of fracture mechanics, the theory of explosion mechanics and rock mass damage, coal and rock damage constitutive model of deep low permeability outburst coal seams under blasting dynamic load will be built. Experimental simulation analysis will be conducted by split hopkinson pressure bar experiment system and the increasing permeability experiment system of cumulative blasting. The optimum preparation methods of cumulative blasting column will be obtained. The effect of coal rock fracture development speed, damage area, the effective time on blasting energy, coal and rock mechanical characteristics will be revealed. The influencing factors of the cutting coal and rock seam for increasing permeability will be gained. Coal and rock permeability change, gas desorption characteristics of rock mass, gas migration regularity and elimination outburst mechanism under blasting dynamic will be explored. The research results will provide theoretical guidance and technical way to improve the effective of pressure relief increasing permeability and rapid coal and gas elimination of the deep low permeability coal.

针对低透气性突出煤层石门揭煤与巷道掘进过程中煤层透气性低，瓦斯难以抽采，瓦斯灾害频发这一特点，通过优化设计聚能药柱，聚能爆轰能量作用下实现煤岩体定向切缝，最大限度内增大煤岩体卸压增透的时效性，获得瓦斯高效抽采，实现深部低透气性突出煤层快速消突。项目以断裂力学、爆炸力学和岩体损伤理论为基础，构建低渗透性突出煤层爆破动载下聚能切缝煤岩体损伤本构模型；依托分离式霍普金森压杆实验系统和深孔聚能低渗透气性煤岩切缝增透实验系统进行试验模拟分析，寻求最佳切缝效应的聚能药柱制备方法，揭示煤岩体裂隙发展速度、损伤范围和有效作用时间与爆破能量、煤岩体力学特性相关参数的影响关系，得出影响煤岩体切缝增透效果因素；探索聚能动载作用下煤岩体渗透率变化以及煤岩体瓦斯解吸特性、运移规律及消突机理。研究成果对提高深部低透气性突出煤层卸压增透、快速消突提供了理论指导和技术途径。

针对低透气性高瓦斯突出煤层石门揭煤与巷道掘进过程中煤层透气性低，瓦斯难以抽采，瓦斯灾害频发以及沿空留巷过程中顶板切割不充分，导致留巷过程中巷道变形严重，效果差等关键技术难题，采用理论分析、实验室相似模拟实验、数值模拟、现场中试实验和现场试验相结合的研究方法，以断裂力学、爆炸力学和岩体损伤理论为基础，得出了爆破动载下聚能切缝煤岩裂隙发育机理；依托分离式霍普金森压杆实验系统和深孔聚能低渗透气性煤岩切缝增透实验系统进行试验模拟分析，系统研究了动静载荷作用下煤岩体破坏作用特性以及相应煤岩体应力应变本构关系，建立了不同应变率响应的煤岩体损伤本构模型，构建了爆破动载作用下聚能切缝煤体损伤和裂隙演化试验系统；得出了爆轰应力波、爆生气体对煤岩体劈裂、裂隙发展的动力学特征规律；通过数值模拟分析了不同煤岩体裂隙演化过程，得出了爆破动载下不同煤岩体裂隙扩展范围。通过现场中试实验，优化了聚能装药结构，确定了两种聚能装药结构，得出了坚硬煤岩体聚能爆破裂隙演化规律与优化参数；研制了聚能爆破早强延迟膨胀型高效封孔材料；研究成果得到了良好的应用，低透气性高瓦斯煤层巷道掘进过程中瓦斯抽采浓度提高2-3倍，抽采纯量提高了5-6倍，抽采35天，残余瓦斯含量降到了6m3/t，掘进速度提高了2-3倍；采用聚能爆破切顶留巷技术，成功留巷970m，巷道变形量很小，完成满足下一工作面安全回采的要求，同时成功在5个工作面推广应用，产生重大的经济和社会效益。