Optimization of direct-hole cutting blasting technology for deep-buried layered surrounding rock diversion tunnels
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摘要:
近些年, 隧道爆破施工向纵深延伸的趋势日渐显著, 而深埋引水隧洞中的层状岩体在爆破施工中对掏槽质量的影响是爆破施工的关键。为研究深埋层状围岩中爆破所在位置对掏槽爆破效果的影响, 以秘鲁圣加旺(San Gabán)水电站引水隧洞爆破开挖工程为依托, 利用ANSYS/LS-DYNA建立了三维有限元数值计算模型, 分析了掏槽爆破产生的损伤区域, 提出了优化方案并进行了现场试验。研究结果表明: 层状围岩分界区域对掏槽爆破产生的岩石损伤范围存在一定影响, 离层状围岩分界区域越近岩石损伤的范围越小; 为增加掏槽爆破的损伤区域, 爆破所在位置要与层状围岩的分界区域保持一定的距离; 对优化后的爆破方案进行了现场试验, 取得了较好的爆破效果。利用数值模拟根据岩石损伤演化规律对掏槽孔位置进行优化, 可提高隧道施工的经济性与安全性。
Abstract:Objective In recent years, the trend of tunnel blasting construction extending to depth is becoming more and more significant, and the influence of layered rock mass in deep buried diversion tunnel on cutting quality in blasting construction is the key to blasting construction.
Methods In order to study the influence of the location of blasting in deep layered surrounding rock on the cut blasting, a three-dimensional finite element numerical calculation model was established by using ANSYS/LS-DYNA, based on the blasting excavation project of the diversion tunnel of San Gabán hydropower station in Peru. The damage area caused by cut blasting was analyzed, and the optimization scheme was put forward for field test.
Results The results show that the boundary area of layered surrounding rock has a certain influence on the range of rock damage caused by cutting blasting. The closer to the boundary area of layered surrounding rock, the smaller the range of rock damage. In order to increase the damage area of cut blasting, the location of blasting should keep a certain distance from the boundary area of layered surrounding rock.
Conclusion The optimized blasting scheme was tested on site and good blasting effect was achieved. In this study, numerical simulation was used to optimize the position of the cutting hole accroding to the law of rock damage evolution, which can improve the economy and safety of tunnel construction.
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Key words:
- blasting damage /
- diversion tunnel /
- cutting blasting /
- numerical simulation /
- layed surrounding rock
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表 1 现场地应力实测值
Table 1. In-situ measured stress values
地应力/MPa 水平应力σx 垂直应力σy 实测值 13.73 12.22 表 2 炸药材料参数
Table 2. Explosive material parameters
ρe/(g·cm-3) ve/(m·s-1) A/GPa B/GPa R1 R2 E0/MPa ω 1.15 4 000 214 0.182 4.15 0.95 4.19 0.15 注:ρe为炸药密度;ve为炸药爆速;其余物理量含义见正文 表 3 炮泥材料参数
Table 3. Mud material parameters
ρm/(g·cm-3) E/GPa μ Etan/MPa fy/MPa β 0.85 11 0.35 2 6 0.1 注:ρm为炮泥密度;E为弹性模量;μ为泊松比; Etan为剪切模量;fy为抗拉强度;β为硬化系数 表 4 空气材料参数
Table 4. Air material parameters
绝热指数γ 参考密度ρ/(kg·m-3) 参考温度/K 恒定体积的比热/(J·kg-1·K-1) 1.4 1.225 288.2 717.3 表 5 岩体材料参数
Table 5. Parameters of the rock mass material
ρr/(g·cm-3) G/GPa T/MPa Pc/MPa Pl/MPa μl μc fc/MPa 2.84 11.57 8 48.8 1.2 0.001 2 0.002 5 146.5 A′ B′ C′ N Smax D1 D2 EFmin 0.3 2.5 0.009 7 0.79 15 0.04 1 0.01 注:各物理量的含义见正文 表 6 爆破效果对比
Table 6. Comparison of blasting effect
方案 炮孔深度/m 循环进尺/m 炸药单耗/(kg·m-3) 原方案 3.2 2.60 3.0 方案一 3.2 2.80 2.7 -
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