N-J水电站岩爆区卸压技术的能量耗散率分析

为研究岩爆区卸压技术的能量耗散率,对巴基斯坦N-J水电站引水隧洞TBM施工的岩爆区进行钻孔卸压和爆破卸压分析,主要对108 mm直径钻孔的卸压应力释放、预裂爆破等情况进行数值模拟,模拟钻孔间距分别为0.5、1.0、1.5、2.0、2.5 m时的孔内钻孔卸压和预裂爆破情况。分析结果表明:预裂爆破卸压法的能量耗散率最高可达到27%,而单纯的钻孔卸压法的能量耗散率最大仅为5.9%,因此预裂爆破卸压的卸压效果远好于单纯的钻孔卸压方法的卸压效果;对于预裂爆破法来说,能量耗散率随卸压孔间距的增加而增大,基本呈指数型增长趋势,对于单纯的钻孔卸压法来说,能量耗散率随卸压孔间距的增加而减小,因此在生产现场应根据不同卸压方法布置合理的钻孔间距。

Energy dissipating rate analysis of N-J hydropower station by pressure relief technique

In order to study energy dissipating rate of stress relief technique, the drill core pressure relief and blasting analysis of rock burst area of TBM diversion tunnel in Pakistan N-J Hydropower Station were carried out. Borehole pressure relief and pre-spliting blasting of 108 mm diameter drill core were simulated. The borehole pressure relief and pre-spliting blasting was simulated in spacing of 0.5, 1.0, 1.5, 2.0 and 2.5 m. The numerical simulation results showed that the stress relief in TBM tunnel could reduce stress concentration phenomenon. The effect of pre-spliting blasting was much better than drill core pressure relief. Energy dissipation rate of pre-splitting blasting pressure relief reached 27%, while the energy dissipation rate of the simple borehole pressure relief method was only 5.9%. Pre-spliting blasting pressure relief method should be used to reduce the pressure in the rock burst area in project site. In the condition of pre-splitting blasting, the relationship between energy dissipation rate and spacing is basically exponential growth trend. For drill core pressure relief, the relationship between energy dissipation rate and spacing is positive correlation. It is important that layout of drill spacing should be reasonable planning.