基于RSM-BBD的煤巷开挖帮部失稳关键因素与控制技术离散元分析

Discrete element analysis of the key influence factors and control technology of coal roadway sidewall instability for excavation based on RSM-BBD design

煤巷围岩是由顶板、两帮及底板组成的整体,帮部强度普遍低于顶底板,是整个巷道围岩的薄弱体,其变形破坏会带来巷道整体失稳。以往大量研究表明,煤巷开挖帮部稳定性主要受煤层埋深、巷道高度、地应力状况、煤体内摩擦角、内聚力及支护强度等设计、地质条件及力学参数类因素影响。本文基于RSM-BBD试验设计与离散元法研究巷帮失稳关键因素及其控制技术。研究结果表明:巷高、侧压系数、埋深可调整余地小,内摩擦角、内聚力、支护强度相对可控,控制巷帮稳定关键在于一定程度上提高煤体内摩擦角、内聚力及支护强度;单一因素及其各自之间交互作用都会影响巷帮稳定性;改善巷帮煤体受力状况,降低主应力差值,提高煤体力学性质,优化掘进工艺水平可有效控制巷帮稳定性;"分次开挖、柔性护表、一次强力支护"理念在现场应用效果良好,显著改善巷帮煤体失稳问题。

The surrounding rock of coal roadway is a whole consisting of roof,sidewall and floor,and the strength of sidewall is generally lower than that of roof and floor.Sidewall is the weak spot of roadway surrounding rock and its deformation and failure will lead to overall instability of roadway.Substantial studies have shown that the stability of coal roadway sidewall for excavation has been mainly affected by the burial depth of coal seam,roadway height,crustal stress states,internal friction angle,cohesion of coal mass,support strength,geological conditions and mechanics parameters.In the present study,the key influence factors and control technology of coal roadway sidewall instability has been researched based on RSM-BBD experiment design and discrete element method.The results have shown that there is little room for the adjustment of roadway height,side pressure coefficient,and burial depth,while internal friction angle,cohesion and support strength are relatively controllable,and the key to control coal roadway sidewall stability is to increase internal friction angle,cohesion and support strength to some degree.Roadway sidewall stability can be affected by single factor and the interactions with each other.The stability of roadway sidewall can be effectively controlled by improving load condition of roadway sidewall coal mass,decreasing principal stress difference,enhancing mechanical property of coal mass and optimizing level of excavation technique.The idea of successive excavation,flexible surface protecting,primary and strong support has been applied to prove its good effects,which significantly improves the instability of roadway sidewall coal mass.