基于加卸载响应比的冲击地压矿井急倾斜巨厚煤层推进速度研究
Study on advancing rate of steeply inclined extra thick coal seam in rock burst mine based on loading unloading response ratio
-
摘要: 工作面推进速度过快易诱发冲击地压等动力灾害,探讨合理的工作面推进速度已成为冲击地压矿井安全高效开采亟待解决的关键。采用数值模拟、岩石力学试验和现场微震监测等方法,通过研究急倾斜巨厚煤层推进速度影响下工作面前方煤体经历的采动应力路径,分析推进速度采动应力路径下的煤样力学行为特征。完成了采动应力路径下煤样加卸载响应比的变化规律研究与急倾斜巨厚煤层工作面推进速度的合理确定,开展了现场工程实践验证。研究结果表明:急倾斜巨厚煤层随工作面推进速度增加使得采动应力峰值增大,同时其采动应力路径的循环加卸载幅度增加,循环次数减小,主要影响区域范围增加,而作用时间减小。不同推进速度应力路径下的煤样强度呈非线性递增趋势,且采动应力路径下的煤样强度普遍大于的常规路径,煤样破坏程度、声发射累计计数及能量均随应力路径所处推进速度的增加而增大。类比冲击矿压评价指标得到6.4m/d应力路径下的煤样可视为冲击煤样,同时引入加卸载响应比,提出了基于采动加卸载响应比的冲击地压矿井工作面推进速度合理确定方法,形成了不同推进速度采动应力路径影响的加卸载响应比评价指标,确定了满足+425水平工作面的安全高效开采推进速度。现场微震实测结果验证了基于采动加卸载响应比确定工作面推进速度的有效性。研究结果为冲击地压矿井工作面的安全高效开采提供了科学指导。Abstract: It is easy for over high advancing rate of working face to induce dynamic disasters such as rock burst. To explore the reasonable advancing rate of working face has become the key to a safe and efficient mining of rock burst mine. Using the methods of numerical simulation,rock mechanics tests and field micro seismic monitoring,by studying the mining stress path experienced by the coal in front of the working face under the influence of the advancing rate of the steeply inclined thick coal seam,the mechanical behavior characteristics of coal samples under the advancing rate mining stress path were analyzed. The study on the change law of loading unloading response ratio of coal samples under mining stress path and the reasonable determination of advancing rate of steeply inclined super thick coal seam were completed and verified by on site engineering practice. The results show that the peak value of mining stress increases with the increase of the advancing rate of the working face in steeply inclined thick coal seam. At the same time,with the increase of advancing rate,the cyclic loading unloading amplitude of mining stress path increases,the cycle times decrease,the main influence area increases,and the action time decreases. The strength of coal samples under different advancing rates stress paths shows a nonlinear increasing trend,and its increasing range increases gradually. The failure degree,cumulative count of acoustic emission and energy of coal samples all increase with the advancing rate of stress paths. The coal sample under the stress path of 6.4 m/d obtained by analogy with the evaluation index of rock burst can be regarded as rock burst. At the same time,the loading unloading response ratio is introduced,and a reasonable method for determining the advancing rate of rock burst mine face based on the mining loading unloading response ratio is put forward. The evaluation index of loading unloading response ratio influenced by different advancing rates mining stress paths is formed,and the safe and efficient mining advancing rate of +425 m level working face is determined. The measured results of micro seismic field verify the effectiveness of determining the advancing rate of working face based on the response ratio of mining loading unloading.