大断面煤巷桁架锚索支护预应力场研究与实践

Study and Practice on Supporting Pre-stress Field of Truss and Anchor Rope in Large Section Coal Roadway

针对大断面煤巷围岩控制难题,分析了高预应力桁架锚索支护技术的优越性。采用FLAC3D模拟分析了大断面煤巷条件下,桁架锚索长度、布置角度、孔口帮距和预紧力对支护预应力场的影响：锚索深入顶板长度以6～8 m为宜,布置角度以15°～20°为合理,孔口帮距为1.4～1.6 m最佳,增大锚索预紧力能大幅减弱岩层的受拉破坏情况,减少顶板岩层下沉。基于此提出了高预应力桁架锚索和常规锚杆索联合控制技术,结果表明：大断面煤巷支护完成15 d后实现自稳,巷道顶板下沉量小于95 mm,两帮移近量小于80 mm,顶板离层量小于5 mm。

Based on the surrounding rock control problem of large section coal roadway,the excellence of truss and anchor rope for large section coal roadway was analyzed. The relationship between supporting pre- stress field and truss and anchor length,angle,distance between orifice and side,pre- tightening force was analyzed by FLAC3 Dnumerical simulation under large section coal roadway.Results show that effectiveness of control was significant when truss anchor length was from 6 m to 8 m,angle was from 15° to 20°,and distance between orifice and side was from 1. 4 to 1. 6 m. What＇s more,rock tension fracture situation and roof subsidence were decreased greatly when pre- tightening force was increased. Based on this,the combined support technology of high pre- stressing truss cable traditional bolt and cable was proposed. Large section coal roadway was self- stabilization after it was digged out for 15 days,roof convergence was less than 95 mm,two sides convergence was less than 80 mm,total roof separation was less than 5 mm.