深部中厚煤层切顶留巷关键技术参数研究

Key parameters of the gob-side entry retaining formed by roof cutting and pressure release in deep medium-thickness coal seams

为保证切顶卸压沿空留巷技术在深部中厚煤层的应用取得成功,结合理论分析、数值模拟及现场实测等方法对深部高应力复合破碎顶板切顶留巷关键参数展开研究.结果表明:当埋深超过第一临界深度后,巷道围岩将呈现出非线性大变形的力学现象,表现在巷道围岩变形量大且稳定时间长,冒落矸石呈现流变特征,同时,预裂爆破会对原有支护造成扰动破坏.在此基础上确定了切缝钻孔间距为600mm,深8m,角度为15°,切缝孔装药结构为4+3+2+0;恒阻锚索靠近切缝线分两列布置,长10m;超前支护距离40m,滞后临时支护距离240m.此外通过对原有挡矸结构进行优化,设计了一种新型可缩U型钢挡矸结构.最终研究成果在城郊煤矿21304工作面成功实施,围岩变形可控,成巷效果好.

To ensure successful application of gob side entry retaining formed by roof cutting and pressure release in deep medium-thickness coal seams,key parameters related to the technique were studied using theoretical analysis,field measurement and numerical simulation.The results show that when the buried depth exceeds the first critical depth,the surrounding rock of the roadway exhibits a nonlinear and large deformation mechanical behaviors,with the deformation of the roadway surroundings being large,the stabilizing time of the retained roadway being long,and the gangues at the gob being rheological.Based on the research results,the separation distance between two adjacent holes was designed to be 600 mm,and the depth of the blasting hole was 8 m.The angle of the hole,with a charging structure of＂4＋3＋2＋0＂,was designed to be 15°.The constant resistance cable,with a length of 10 m,was used to support the roof in two rows near the cutting line.The advanced supporting distance was set to be40 mand the lagging temporary supporting distance was 240 m.In addition,by optimizing theoriginal gangue prevention structure,a new type of retractable U steel gangue prevention structure was designed and applied.The research results were successfully applied at No.21304 working face in Chengjiao coal mine.Field monitoring indicates that the deformation of the retained entry was controllable,and the final retaining effects were good.