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小构造与开采扰动下深井煤巷应力演化规律与能量分源控制

Stress evolution law and energy source control of deep coal roadway under small geological structure and mining disturbance

  • 摘要: 当煤炭开采进入深部以后,高地应力、复杂地质构造和强采掘扰动特征愈发明显。针对深井煤巷受应力扰动导致掘进过程中两帮变形严重且难以控制的问题,研究了小构造与回采扰动下掘进巷道应力演化规律。基于井下底板岩巷穿层瓦斯抽采钻孔数据点云重构了工作面的三维地质模型,辨识出了掘进巷道途中存在的倾斜煤层、连续褶曲和煤层变薄带。并利用建成的三维模型,导入FLAC3D软件中模拟煤巷掘进与邻近工作面回采。结果表明:在小构造区域,掘进工作面处的峰值压应力更大,压应力随掘进距离的变化率也更高。倾斜煤层、连续褶曲和煤层变薄带处的峰值压应力最大值分别为19.62、19.25、19.86 MPa,压应力变化率的最大值分别为16.12%、12.8%、11.51%。而厚度均匀的煤层掘进时最大压应力不超过19 MPa,压应力变化率的最大值不超过10%。回采距离较小时,掘进应力与回采应力互不干扰;随着回采距离增大,掘进巷道围岩位移增大,回采应力不断扩展,逐渐起主控作用,对掘进巷道产生强应力扰动。在现场采取穿层钻孔水力冲孔与注浆加固强弱耦合结构能量分源控制方法后,降低了煤层瓦斯含量和压力,增强了巷道围岩强度,两帮位移量减小了57%,显著降低了煤岩动力灾害发生的概率与风险。该研究可以为有效保障深井煤巷的安全采掘提供基础理论支撑。

     

    Abstract: When coal mining enters the deep, the characteristics of high ground stress, complex geological structure and strong mining disturbance become more and more obvious. Aiming at the problem that the deformation of two sides is serious and difficult to control in the process of excavation due to stress disturbance in deep coal roadway, the stress evolution law of excavation roadway under small structure and mining disturbance is studied. Based on the point cloud data of the gas drainage borehole group in the underground floor rock roadway, the three-dimensional geological model of the working face was reconstructed, and the inclined coal seam, continuous fold and coal seam thinning zone in the roadway were identified. The three-dimensional model is imported into FLAC3D to simulate the coal roadway excavation and working face mining. The results show that in the small geological structure area, the peak compressive stress of the tunneling head is larger, and its change rate with the tunneling distance is also higher. The maximum values of peak compressive stress at inclined coal seam, fold and thinning zone are 19.62, 19.25 and 19.86 MPa, respectively, and the maximum values of compressive stress change rate are 16.12%, 12.8% and 11.51%, respectively. The maximum compressive stress is not more than 19 MPa and the maximum change rate of compressive stress is not more than 10% when the coal seam with uniform thickness is excavated. When the mining distance is small, the excavation stress and the mining stress do not interfere with each other; as the mining distance increases, the displacement of the surrounding rock of the excavation roadway increases, and the mining stress continues to expand, gradually playing a dominant role, causing strong stress disturbance to the excavation roadway. After adopting the energy source control method of strong-weak coupling structure of hydraulic punching and grouting reinforcement in the field, the gas content and pressure of the coal seam are reduced, the strength of the surrounding rock of the roadway is enhanced, and the deformation of the two sides is reduced by 57%, which significantly reduces the probability and risk of coal-rock dynamic disasters. This study can provide basic theoretical support for effectively ensuring the safe mining of deep coal roadway.

     

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