高位硬厚岩层影响下矿震发生规律及预测

Mining earthquake incidence features and forecast under the impact of the top-level hard and thick rock and coal seams

为系统有效地预防灾害性矿震,以东滩煤矿43上13工作面为背景,运用理论分析、数据和统计分析等方法,研究了高位硬厚岩层影响下灾害性矿震的机理和发生规律,在此基础上对43上13工作面剩余部分矿震危险做出预测。高位硬厚岩层条件下发生矿震的根本原因是硬岩运动释放较大能量与采动应力在老顶附近相遇并叠加,可能诱发冲击破坏。东滩煤矿43上13工作面高位砂砾岩运动为矿震发生提供巨大动力源,是主导矿震的关键因素。从震源与断层关系可以看出震源有沿断层展布而分布的特征。大矿震发生前后的支架阻力异常不稳定,振幅增大,频率增高,往往经历一段时间的蓄能期,矿震发生具有明显的周期特性,这种周期特性在东滩煤矿43上13工作面表现为100 m的大周期内存在50 m的小周期,1个大周期大致对应6个基本顶周期来压;1个小周期大致对应3个基本顶周期来压,大小周期内分别发生4次和2次左右高能矿震。工作面开采速度过大或剧烈变化会导致强矿震的发生,回采过程中要格外注意对开采速度的限制并尽量保持匀速开采。最后将矿震预测结果与现场实际情况进行了对比验证。

The paper is to make a systematic exploration of the mechanism and the corresponding characteristic features of the disastrous mining earth-shock due to the impact of the top-level hard thick rock unexpected shaking of the coal seams. For the said purpose, it is necessary to predict and forecast the engineering background of the 43up13 working face in the case of Dongtan Coal Mine, whose earthquake risk threats have been existing in the remainilag portions of the working faces. So far as we know, the basic reason that may account for the disastrous mining shocks is that there exist great amounts of dynamic force induced by the hard thick rock seams movement at the higher levels due to the mining stress near the main roof and the destructive force of the rock bursts. Therefore, the movement of the high-position glutenire in the 43up13 working face of the mine tends to be a huge power source likely to lead to the mining earth shocks, which may serve as the key factor leading to the mining shocks or bursts. The study results we have done indicate that there exists an underlying relation between the mining earthquake sources and the earth-thrust faults, signifying that the mining earthquake sources tend to distribute in a linear form related with the band of the mining faults. Therefore, the supporting resistance of the hydraulic support is likely to become extremely instable and fallible whenever the great shock of the high energy mining earthquake occurs, which may lead to the increase of the amplitude and frequency of the corresponding resistances. Besides, there has always been existing a period of energy accumulation and storage before the high energy mining＂ earthquake breaks out in a surrounding cycle of about 100 m long whenever a mining shock occurs, which demonstrates that the gap between the great distance cycle and that of the small cycle would be at about 50 m in the aforementioned working face of the mine. In addition, the great distance cycle may roughly correspond to the 6 periodic pressures of the main roof whereas the small one should roughly correspond to the 3 periodic ones of the main roof. Thus, it would imply that 4 and 2 times such high energy mining shocks are likely to occur isolate in their distance cycles. This also implies that, if the mining speed of the said working face were too great or too abrupt, the change would be inevitable to lead to more strong mining quakes. Therefore, it is of particular attention to be paid to the restriction of the mining speed and proper regularity of the mining speed lest the mining disasters would occur. Besides, it is also necessary to compare the prediction results of the mining quakes with the actual mining status-in-situ under study.