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为了对N-J水电站引水隧洞岩爆区进行卸压分析,对施工区的SS-1砂岩进行岩爆倾向性试验,采用弹性能量指数作为岩爆倾向判断指标,试验结果表明施工区具有强烈的岩爆倾向,说明了进行钻孔卸压的必要性。运用扩展有限元方法对钻孔预裂爆破进行数值模拟,模拟不同抗拉强度的岩体(4、6、8、10 MPa)在不同钻孔间距(0.5、1.0、1.5、2.0、2.5 m)的孔内预裂爆破情况,分析了爆破过程的能量耗散率、裂缝贯穿最小冲击力等。数值分析结果表明:预裂爆破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;岩爆区的计算冲击应力小于岩石极限动态抗拉强度时,爆破不会使钻孔壁产生压碎破坏;在施工现场应对钻孔间距进行合理布局,以保证良好的卸压效果。
In order to analyze the pressure relief of the rock burst area of the diversion tunnel of NJ Hydropower Station, the rockburst propensity test of SS-1 sandstone in the construction area is conducted. The elastic energy index is taken as the judgment index of rock burst tendency. The test results show that the rock burst Tendency, illustrates the need for pressure relief drilling. The extended finite element method is used to simulate the pre-splitting blasting of boreholes. The rock masses with different tensile strengths (4, 6, 8 and 10 MPa) are simulated in different borehole spacing (0.5, 1.0, 1.5, 2.0 and 2.5 m) Of the hole pre-cracking blasting situation, analysis of the energy dissipation rate of the blasting process, cracks through the minimum impact and so on. The results of numerical analysis show that the energy dissipation rate of presplit blast increases with the increase of pressure relief hole spacing and increases exponentially. When the calculated impact stress of rock burst zone is less than the ultimate dynamic tensile strength of rock, blasting does not make Drilling wall crushing damage; drilling holes in the construction site should be reasonable layout to ensure a good pressure relief effect.