工作面动压影响下老窑破坏区煤柱应力状态研究

STUDY OF STRESS STATE OF COAL PILLAR IN FAILURE ZONE OF COAL SEAM UNDER DYNAMIC PRESSURE OF MINING

通过调研汾西矿区内老窑破坏区地质条件、顶底板岩体特性及水文条件,利用瞬变电磁法对汾西矿区新柳煤矿典型老窑破坏区进行精细地质探测,并在地质探测基础上构建破坏区相似模型,分析破坏区内煤柱应力状态受工作面回采动压影响的变化规律。结果显示,工作面回采过程中,开始阶段煤柱应力一直维持在初始状态,基本无变化。当距工作面62.5m左右时,煤柱应力开始增大;距离工作面12.5~25.0 m时,煤柱应力骤然增大。回收煤柱时,由于受工作面动压的影响,工作面前方煤柱内的弹性核处于高度受压状态,一直处于较高的应力水平,而且弹性核随着工作面的推进逐渐前移,对工作面的安全回采造成极大危害。因此,应当采取超前卸压的措施破坏煤柱内的弹性核,以保证煤柱回收工作安全高效地进行。

The field investigation of the geological conditions, the physico-mechanical characteristics of the surrounding rock and the hydrological conditions of mining areas in Fenxi, together with an intensive geological detection with the method of transient electromagnetic in the typical failure zones in Xinliu coal mine was carried out. A similarity model of the failure zones was developed based on the results of the geological detection and the stress state in the pillar affected by the dynamic pressure during mining was studied. The stress state of pillar changes little and remains the initial state within a period of time in the process of longwall mining. The increase of pillar stress occurs firstly at the distance of 62.5 m ahead of the working face, while a significant accumulation appears at the pillar 12.5 - 25.0 m ahead of the longwall mining face. In the process of pillar extraction, the high compression stress controls the elastic core in the pillar and remains at a high level under the effect of dynamic pressure. Meanwhile, the elastic core moves forward along with the advancing of the longwall mining face and bring about the severe risks to the coal mine. Therefore, the elastic core should be destroyed by pre-unloading, so as to ensure the safety in pillar extraction.