采空区影响条件下巷道围岩应力监测与研究

Monitoring and research on surrounding rock stress in roadway under the influence of goaf

金属矿采空区多以矿房-矿柱组合的复杂采空群体系构成,这种复杂的空区群结构是一种复合应力拱的承载结构,复合应力拱的成拱机制形成了采场上方覆岩发生拉压破坏模式,进而导致围岩塌陷及巷道破坏;为了监测采空区影响下巷道围岩复合应力变化,提出在巷道内利用锚杆应力计监测围岩复合压力拱应力变化方法,锚杆采用端部锚固结构,埋入深度超过围岩冒落带并施加预应力;根据监测数据分析围岩应力变化可分为递变式、突跳式、振荡式和复合式变化四种变化模式,利用多元回归及突变模型建立围岩应力变化的数学模型,以历史数据为基础,建立以围岩应力极限值、应力变化速率及突变模型势函数临界值为判据的围岩稳定性分析数学模型。

The goaf of metal mine is mainly composed by complex goaf group system with room-pillar combination, and this complex goal group structure is a bearing structure with complex stress arch. The arching mechanism of complex stress arch causes the tension and compression failure mode happening in overlying strata above the stope, which leads to the collapse of surrounding rock and failure of roadway. In order to monitor the change in complex stress of roadway surrounding rock under the influence of goaf, the method of using anchor stress gauge to monitor the stress variation of complex pressure arch in roadway surrounding rock was put forward. The archor adopts end anchor structure, the buried depth exceeds the surrounding rock caving zone, and it was inflicted with pre-stress. Based on the monitoring data analysis, the variation of surrounding rock stress can be divided into four modes, including gradation type, sudden jump type, oscillation type and compound type. By using multiple regression and catastrophic model, the mathematical model on variation of surrounding rock stress was established. Taking the his- torical data as foundation, the mathematical model on stability of surrounding rock was established, with taking the limit value of surrounding rock stress, the variation rate of stress and the critical value of potential function in catastrophe model as criteria.