上保护层煤柱引发被保护层冲击机理研究

长城一矿和峻德煤矿所发生的由保护层煤柱引发冲击的案例表明,保护层煤柱影响范围内仍属高应力区,且工作面上方都存在坚硬的顶板。通过分析两起事故中被保护层煤体的赋存条件,探究发生此类冲击的影响因素。研究表明,典型的保护层煤柱诱发冲击主要有以下两种情况:(1)大采深小层间距下,以"高静应力为主,低动应力诱发"型冲击;(2)中等采深大层间距下,以"高动应力为主、低静应力诱发"型冲击。静力系由煤柱传递的应力和层间岩体的自重应力以及保护层采空区的残余支承压力组成,动力系主要是本煤层已开采工作面形成的侧向支承压力。建立了判断发生冲击地压的评估方法,为此类矿井的开采提供理论依据。并提出了工作面位置设计、合理布置巷道、预前卸压、加强监测的防治措施。

Mechanism of rockburst occurring in protected coal seam induced by coal pillar of protective coal seam

The rockburst accidents in Changchengyi Coal Mine and Junde Coal Mine show that high abutment stress exists in the affected area of the pillar of the protective seam, and that hard roof exists above the longwall panel. By comparing the occurrence conditions of the two accidents, the main factors causing the rockburst accidents in the protected coal seam are analyzed. The results indicate that due to the coal pillar of the protective seam, two types of rockburst accidents may be induced. (1) With a large burial depth and small seam distance, the accident is induced by high static stress (the main factor) and low dynamic stress (the minor factor). (2) With a medium burial depth and large seam distance, the accident is induced by high dynamic stress (the main factor) and low static stress (the minor factor). The static stress (mainly affected by burial depth) is mainly composed of the transfer stress resulting from the coal pillar, and the self-weight stress caused by the strata between the two seams, and the residual abutment stress of the gob that is situated on the same level with the protective coal seam. The dynamic stress is mainly the lateral abutment stress of the gob that lies on the same level with the protected coal seam. In addition, the evaluation method for rockburst is established, and it may provide a theoretical basis for mines with similar geological conditions. Finally, some treatment measures, such as design of the position of the longwall panel, rational arrangement of roadways, stress pre-releasing and enhancement of monitoring, are proposed.