厚硬顶板直覆型沿空巷道冲击失稳机理及防治研究

Research on the Impact Instability Mechanism and Prevention of Gob-Side Entry Retaining with Direct-Covering Thick and Hard Roof

基于厚硬顶板直覆型沿空巷道冲击失稳问题,以山东某矿63_上06工作面沿空巷道为工程背景,采用现场实测、理论分析、数值模拟相结合的研究方法,分析直覆型顶板破断特征、释能机制及沿空巷道冲击失稳能量判别准则,阐明厚硬顶板直覆型沿空巷道冲击失稳机理。研究结果表明:厚硬顶板直覆采场“板-壳”覆岩结构失稳演化具有周期长、覆岩运移控制范围广及顶板破断动载突出的特征,相比一般巷道,厚硬顶板直覆型巷道受动载扰动影响更加突出;受直覆型厚硬顶板大范围悬顶影响,“板-壳”覆岩结构运动将会增加沿空巷道超前静载,同时会向下传递剧烈动载,两者共同作用使直覆型厚硬顶板破断产生超强动载,从而引起巷道发生冲击失稳;现场实例表明,直覆型厚硬顶板初次破断尺寸为58 m,破断释放能量为3.5×10^(7)J,传递至巷道的能量为8.9×10^(5)J,周期破断尺寸为28 m,释放能量为1.7×10^(7)J,传递至巷道的能量为4.36×10^(5)J,小于63_(上)06沿空巷道临界冲击能量1.25×10^(6)J,表明常规条件下直覆型厚硬顶板初次破断或周期破断不会诱发巷道冲击失移;提出了“工作面匀速或低速开采+直覆厚硬顶板深孔爆破预裂+强化超前支护”的综合防控对策,并在煤矿现场进行了工业性试验。研究成果可对类似工程地质条件下厚硬顶板直覆型沿空巷道冲击失稳防控提供一定参考。

Based on the problem of impact instability of gob-side entry retaining with direct-covering thick and hard roof,taking the gob-side entry retaining of 63upper06working face of a mine in Shandong Province as the engineering background,the research methods of field measurement,theoretical analysis and numerical simulation were used to analyze the breaking characteristics and energy release mechanism of direct-covering thick and hard roof and energy criterion of impact instability of gob-side entry retaining.Then,the mechanism of impact instability of gob-side entry retaining with direct-covering thick and hard roof was clarified.The results show that the instability evolution of the“plate-shell”overburden structure in the stope with direct-covering thick and hard roof has the characteristics of long period,wide range of overlying strata migration control and prominent dynamic load of roof breaking.Compared with the general roadway,this kind of gob-side entry retaining is more affected by dynamic load disturbance.Affected by the large-scale hanging strata of the direct-covering thick and hard roof,the movement of the“plate-shell”overburden structure will increase the advanced static load of the gob-side entry retaining,at the same time,it will transmit severe dynamic load downward.The combined action of the static load and dynamic load causes the direct-covering thick and hard roof to break and produce super-strong dynamic load,which causes the impact instability of the gob-side entry retaining.The field case shows that the initial fracture size of the direct-covering thick and hard roof is 58m,the fracture release energy is 3.5×10^(7) J,and the energy transmitted to the gob-side entry retaining is 8.9×10^(5) J;the periodic fracture size is 28m,the release energy is 1.7×10^(7) J,and the energy transmitted to the gob-side entry retaining is 4.36×10^(5) J,which is less than the critical impact energy 1.25×10^(6) J of the 63_(upper)06gob-side entry retaining,indicating that the initial fracture or periodic fracture of the direct-covering thick and hard roof will not induce the impact displacement of gob-side entry retaining under conventional conditions.The comprehensive prevention and control measures of“uniform or low speed mining of working face+deep hole blasting pre-splitting of direct-covering thick and hard roof+strengthening advanced support”were put forward,and industrial tests were carried out on the coal mine site.The research results can provide some reference for the prevention and control of impact instability of gob-side entry retaining with direct-covering thick and hard roof under similar engineering geological conditions.