College of Mining Engineering,Taiyuan University of Technology
Key Laboratory of In-situ Property Improving Mining of Ministry of Education,Taiyuan University of Technology
College of Mechanical and Vehicle Engineering,Taiyuan University of Technology

切顶卸压自成巷无煤柱开采是综采工作面实现连续生产、快速衔接、提高煤炭采出率的重要采煤工艺,能有效避免矿井发生重大地质灾害事故,是煤矿可持续发展的方向之一,其中切缝关键参数对留巷围岩稳定性具有较大影响。为控制工作面开采后沿空留巷围岩的变形量,保证巷道结构的稳定性,以青云煤矿020201工作面为工程背景,分析其缓倾斜煤层切顶成巷特点,提出两种切缝角度确定方法,同时结合现场生产条件研究了切缝位置对切顶卸压沿空留巷稳定性的影响。研究结果表明:切缝角度及切缝位置的选择影响留巷顶板的运移特征,依据岩层垮落角确定了2.7°切缝角度,并得出在挡矸墙采空区侧进行切顶时,切缝可切断采空区顶板压力向留巷上方传递荷载的路径,弱化了顶板断裂活动对留巷的影响,有利于实现留巷围岩控制的目的;现场矿压监测结果表明,在采动作用下,采用合理的锚网支护可形成稳定结构,切顶卸压效果明显,对于切顶成巷技术在缓倾斜煤层开采中的推广应用具有借鉴意义。

The gob-side entry retained by roof cutting coal pillarless mining technique is important for continuous production,rapid connection and improvement of coal recovery rate in the fully-mechanized mining face. It can effectively avoid major geological disasters in mines and it is one of the sustainable development methods of coal mines. For the gob-side entry retained by roof cutting,the key roof pre-fracturing parameters have a significant influence on the stability of the gob-side entry retained. To control the deformation of surrounding rocks of gob-side entry retained and ensure its stability,the characteristics of gob-side entry retained in gently inclined coal seam wereanalysised by taking Qingyun Coal Mine 020201 working face as the engineering background. Two methods were proposed to deterimine the dip angle of the roof pre-fracturing borehole to the goaf. At the same time,the influence of the roof pre-fracturing borehole position on the stability of the gob-side entry retained was studied considering the field production conditions. The results show that the dip angle and position of the roof pre-fracturing borehole affect the movement characteristics of the overlying rock strata. When the dip angle of the roof pre-fracturing borehole is 2.7° and the boreholes are arranged on the goaf side of the retaining wall,the load transfer path from the goaf to the gob-side entry retained can be effectively cut off and weaken the impact of roof fracture activities on the gob-side entry,which is beneficial to the ground control of the gob-side entry. Field mine pressure monitoring shows that the reasonable anchor-net support can ensure the formation of a stable rock structure in the roof of gob-side entry, and the roof pre-fracturing effect is obvious,which has significance for the promotion and application of gob-side entry retained by roof cutting in gently inclined coal seam.

山西省应用基础面上基金资助项目(20210302123124);山西省应用基础青年基金资助项目(201901D211066)