工作面单双巷顶板爆破应力演化规律研究

Stress evolution law of single and double roadway roof blasting in working face

坚硬顶板是影响工作面冲击危险的重要因素,实践中常采用爆破技术对工作面顶板进行预裂和卸压。以田陈煤矿3煤层上方存在坚硬顶板的7202工作面为对象,采用理论分析、数值模拟、工业试验等方法,研究了不同爆破高度、工作面单巷和双巷顶板爆破下围岩应力演化及微震规律。结果表明:针对低位亚关键层采用单巷和双巷爆破时,爆破高度越大,巷道围岩峰值应力越低,卸压效果与爆破高度呈正相关关系;但采用双巷爆破时,当爆破高度增加至6倍采高(亚关键层中部位置)以上时,工作面中部区域会出现应力升高现象,且工作面越短应力升高越明显;在7202工作面初采阶段进行高度为3倍采高的单巷顶板爆破时,微震多集中在巷道区域,卸压效果一般,改为双巷顶板爆破并提高爆破高度至6倍采高后,微震多集中到工作面中部区域,无大能量微震事件发生,应力监测预警次数也大幅降低,巷道区域卸压效果较好。

Hard roof is an important factor affecting the burst risk of the working face,and blasting technology is often used in practice to pre-split and relieve pressure on the working face roof.We took the 7202 working face with a hard roof above the No.3 coal seam of Tianchen Coal Mine as the object,applied methods such as theoretical analysis,numerical simulation,and industrial tests to study the stress evolution of surrounding rock and the law of micro-seismic events under different blasting heights,single and double roadway roof blasting in the working face.The results show that when using single or double roadway blasting for low level sub-key stratum,the higher the blasting height,the lower the peak stress of the surrounding rock in the roadway,and the pressure relief effect is positively correlated to the blasting height.However,when using double roadway blasting and increasing the blasting height to more than 6 times the mining height(at the mid-section of the sub-key strata),the stress increases in the central area of the working face,and the shorter the working face,the more obvious the stress increase.During the initial mining stage of the 7202 working face,when single roadway roof blasting with a height of 3 times the mining height was carried out,the microseisms were mostly concentrated in the roadway area,and the pressure relief effect was moderate.After changing to double roadway roof blasting and increasing the blasting height to 6 times the mining height,the microseisms were mostly concentrated in the central area of the working face,without the occurrence of high -energy micro -seismic events. The number of stress monitoring warnings was alsosignificantly reduced,and the pressure relief effect in the roadway area was favorable.