黄陵矿区综采工作面卸压瓦斯运储区演化规律分析及工程实践

Evolutionary pattern of pressure-relief gas transportation-storage area in fully mechanized mining face and its engineering practice in Huangling minefield

  • 摘要: 煤层开采诱发的覆岩裂隙结构演变,对采空区卸压瓦斯运移与储集具有较大影响。为了确定黄陵矿区综采工作面高强度开采上覆岩层裂隙网络中卸压瓦斯运移与储集区动态演化规律,以黄陵二号煤矿213工作面为基础原型,通过二维物理相似模拟实验研究该综采工作面在高强度开采过程中支承压力变化、岩层移动以及覆岩裂隙分布特征;依据裂隙形态对卸压瓦斯运储区进行判别,明确了卸压瓦斯运移通道与储集区的判别方法,得到卸压瓦斯运储区演化规律,并以此为基础,提出了基于卸压瓦斯运储区位置、瓦斯涌出强度的卸压瓦斯抽采技术选择流程,优化了常规高位钻孔与定向长钻孔布置层位。研究结果表明:覆岩垮落后采动垂直应力分布大致呈对称类梯形,岩层位移分布均呈现趋于对阵的梯台形;卸压瓦斯运移与储集区可划分为4个区域,分别为卸压瓦斯储集优势区、运移优势区、微渗区及运−储优势区。根据相邻工作面历史瓦斯涌出量数据及试验工作面含瓦斯量,选择定向长钻孔辅以常规高位钻孔的卸压瓦斯抽采模式,设计并优化了钻孔布置参数,工作面回采期间抽采钻孔内瓦斯体积分数可长时间稳定在30%以上,工作面、回风巷及上隅角等重点区域瓦斯体积分数分别控制在0.18%~0.46%、0.2%~0.46%以及0.25%~0.84%,均远低于相关规定最大值。工程实践结果表明,依据卸压瓦斯运储区分布特征设计抽采钻孔,可有效提高卸压瓦斯抽采效率,保障工作面安全高效生产。

     

    Abstract: The evolution of overburden fracture structure induced by coal seam mining has a greater impact on the transportation and storage of pressure-relief gas in the mining zone. To determine the dynamic evolution law of pressure-relief gas transportation-storage area in the fracture network of the overlying rock strata on the condition of high-intensity mining in Huangling minefield, the change of supporting pressure, the rock strata movement, and the overlying rock fracture distribution are clarified through the physical similarity simulation experiment using the No. 213 working face of the No. 2 Coal Mine of Huangling Minefield as a basic prototype. Based on the fracture morphology of the pressure-relief gas transportation-storage area, the identification method of the pressure-relief gas transportation channel and storage area was clarified, and the evolution law of the pressure-relief gas transportation and storage area was obtained. The selection process of unloaded gas extraction technology based on the location of the pressure-relief gas transportation-storage area and the intensity of gas outflow is proposed. And the layers of conventional high-level boreholes and directional long-drill holes are optimized. The results show that the vertical stress distribution and the displacement distribution of the rock layer are symmetrical trapezoidal after overburden collapsed. The pressure-relief gas transportation-storage area can be divided into 4 zones which are the pressure relief gas storage advantage zone, transportation advantage zone, micro-seepage zone and transportation-storage advantage zone. Based on the historical gas outflow data of the adjacent workface and the gas content of the test workface, the pressure-relief gas extraction mode of directional long boreholes supplemented by high-level boreholes was selected, and the parameters of the borehole arrangement were optimized. The volume fraction of gas in the extraction boreholes can be maintained above 30% for a long period of time during mining. The volume fraction of gas in the working face, the return airway and the upper corner was controlled at 0.18%−0.46%, 0.2%−0.46% and 0.25%−0.84% respectively, which were far below the maximum value of the relevant regulations. The results of engineering practice show that the design of extraction boreholes based on the distribution characteristics of the pressure-relief gas transportation-storage area can effectively improve the efficiency of unloaded gas extraction and ensure the efficient production of the working face.

     

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