煤矿深部特厚煤层综放开采覆岩裂隙场演化应用基础研究

The top coal caving mining has an advantage of high yield and high efficiency, it has been used widely in thick coal seam mines of China, especially in most of safety and high efficient mines, and TCCM is also the main development direction of other coal production countries in the world in thick coal seam. Since absolute gas emission at TCCM face is higher, only by the method of strengthening ventilation, can the phenomenon of gas limit not be solved. According to geological conditions of TCCM of hugely-thick conglomerate layer, deep, easily-spontaneous combustion, and extremely-thick coal seam with low gas density in Yima mining area, China, from the continuous mining point of view to control the phenomenon of gas limit, the project carries through high position drilling or roadway to extract gas over the gob, based on the fact of that gas into fractured zone over gob accounts for most of gas emission quantity of TCCM face, and roof weighting influences on the gas emission quantity of the face. The project studies the damage evolution time-space law of overlying coal-rock mass fissures at deep TCCM face, the characteristics of forming structures and deformation instability caving for top coal and roof strata, and relationship between height of caved zone and fractured zone and coal seam thickness. Damage deformation mechanical model for roof coal and rock mass at TCCM face is established, the moving law of roof coal and gangue is studied. The conclusions provide theoretical basis for arranging high position drilling, choosing reasonable roof strata to layout gas-drainage roadway, improving top coal recovery ratio, and safety and high efficiency product at TCCM face.

放顶煤开采具有产量高和效益好的特点，在我国厚煤层煤矿特别是绝大多数安全高效矿井中已经得到了广泛的应用，目前也是世界其它采煤国家厚煤层开采发展的主要方向。但放顶煤工作面绝对瓦斯涌出量大，仅靠加强通风难以解决工作面瓦斯超限问题。项目针对义马矿区巨厚砾岩层下，深部、低瓦斯易自燃特厚煤层综放开采地质条件，基于采空区顶板裂隙带瓦斯占采面瓦斯涌出量的大部分、顶板来压影响到采面瓦斯涌出量的现状，进行高位抽放采空区瓦斯，从连续开采的角度治理采面瓦斯超限问题。项目研究深部综放开采上覆煤岩体裂隙损伤演化时空规律，研究综放面顶煤、顶板岩层形成结构和变形失稳垮落特征，以及垮落带和裂隙带高度与煤层厚度之间的关系，建立深部综放工作面顶板煤岩体损伤变形力学模型，研究深部综放面顶板煤矸流动规律。研究结论为综放开采高位抽放钻孔布置和高抽巷道合理位置选择、顶煤回收率的提高，以及综放工作面安全高效生产提供理论基础。

综采放顶煤采煤法具有产量高和经济效益好的特点，在我国煤矿特别是绝大多数厚煤层安全高效矿井中已经得到了广泛的应用。但综放面产量高、绝对瓦斯涌出量大，靠增加工作面供风量加强通风，仍难以解决工作面瓦斯超限问题。针对义马矿区开采的煤层属于缓倾斜、易自燃、特厚煤层，上覆浅部岩层中存在一层平均厚度240m的巨厚砾岩层的工程地质条件，项目采用现场观测、实验室试验、数值计算以及理论分析方法，研究了义马矿区综放面围岩性质和巨厚砾岩层赋存特征、综放面矿压显现规律和地面变形移动规律；阐明了综放开采围岩应力场、位移场和裂隙场的特征、上覆煤岩层和浅部巨厚砾岩层裂隙萌生、扩展和演化规律；阐明了综放开采围岩应力场、位移场和裂隙场的特征、上覆煤岩层和浅部巨厚砾岩层裂隙萌生、扩展和演化规律；利用厚板理论建立了综放开采巨厚砾岩层初次破断步距计算理论模型，推出砾岩层厚板初次破断步距与其抗拉强度之间的非线性关系；建立了综放面顶板煤岩体损伤变形力学模型，研究了综放面放煤过程中顶煤和顶板岩石流动规律、放顶煤工艺，以及放顶煤参数对顶煤回收率的影响，确定了合理的放顶煤参数；提出了高抽巷合理层位、低位钻场间距和高位钻孔高度的计算方法。综放面瓦斯涌出的高峰出现在顶板周期来压之后的数日内，综放面矿压显现对工作面瓦斯涌出影响较大。该项目从综放面围岩控制的观点，提出了综放面高抽巷和高位钻孔的采空区瓦斯抽采技术，解决了综放面上隅角的瓦斯超限问题。项目研究成果已经在义马矿区耿村煤矿、千秋煤矿和常村煤矿综放面瓦斯综合治理中进行了现场应用，取得了显著的技术和经济效益。研究成果为综放开采高位抽放钻孔布置和高抽巷道合理位置选择，以及综放面连续安全高效生产提供了理论基础。