Optimum seam forming angle of bilinear shaped charge in engineering blasting
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摘要: 为探究聚能张开角对双线型聚能药包结构炸药有效利用率和聚能效应的影响,通过瞬时爆轰假说理论对有效聚能炸药边界方程进行推导,分析不同聚能张开角聚能装药结构炸药的有效利用率;通过水泥砂浆物理模型试验,研究不同聚能张开角预裂孔成缝规律;采用LS-DYNA数值模拟软件,建立不同聚能张开角数值模型,揭示不同聚能张开角的双线型聚能结构药包射流的侵彻过程。研究结果表明聚能张开角为75°时,炸药产生聚能效应的有效利用率最大;聚能结构药包聚能槽张开角为75°时,预裂孔成缝效果明显优于聚能槽张开角为60°的聚能结构药包,沿聚能槽方向应力集中效应和侵彻深度最佳,炮孔壁上岩石单元最先达到应力峰值。针对聚能张开角为75°的双线型聚能结构药包开展了不同岩性预裂爆破现场试验,板岩和白云岩两种不同岩性,在孔距增大20%的条件下,双线型聚能预裂爆破效果优于常规预裂爆破。Abstract: To explore the influences of the opening angle of bilinear shaped charge on the effective utilization rate and energy gathering effect, the boundary equation of effective shaped charge was deduced through the theory of instantaneous detonation hypothesis. The effective utilization ratio of the shaped charge structure blasting with 60°, 65°, 70°, 75°, and 80° shaped charge angles was analyzed using the visual implicit functions of SymPy package based on Python language. Through the physical model tests of single-hole Plexiglas and double-hole cement mortar, the crack formation law of pre-cracked holes with different energy-gathering opening angles was studied. Using the LS-DYNA numerical simulation software, five numerical models with energy-gathered opening angles of 60°, 65°, 70°, 75°, and 80° were established to reveal the penetration process of the bilinear energy-gathered structure charge jet and the stress evolution law of the rock unit on the blast-hole wall with different energy-gathered opening angles. The research results show that the effective utilization ratio of the shaped explosives is the highest when the energy-gathered opening angle is 75°. The pre-split hole formation effect when the opening angle of the energy-concentrating groove of the shaped charge is 75° is better than that when the opening angle is 60°, and the stress concentration effect and penetration depth along the direction of the energy-concentrating groove are the best, and the rock unit on the blast-hole wall reaches the peak stress first. The pre-split blasting field tests of two lithologies of Slate and Dolomite were carried out for the double-line shaped energy-concentrated structure charge with the energy-gathering opening angle of 75°. In two different lithologies of Slate and Dolomite, under the condition that hole spacing was increased by 20%, the double-linear pre-split blasting effect of the shaped energy is better than that of the conventional pre-split blasting.
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表 1 炸药性能参数
Table 1. Explosive performance parameters
炸药类型 爆速/(m·s−1) 密度/(g·cm−3) 爆热/(kJ·kg−1) 熔点/℃ 爆燃点/℃ 外观 黑索金 8750 1.89 6025 205 230 白色结晶粉末 表 2 试验爆破参数
Table 2. Test parameters
组号 类型 药包直径/mm 装药量/g 炮孔深度/mm 炮孔直径/mm 备注 1 普通 6 0.6 80 8 无需定位 2 双线型聚能 6 0.6 80 8 需定位 表 3 水泥砂浆试件静态力学参数
Table 3. Static mechanical parameters of cement mortar
纵波波速/(m·s−1) 密度/(g·cm−3) 抗压强度/MPa 抗拉强度/MPa 泊松比 弹性模量/GPa 1 810 2.41 5.13 0.45 0.213 7.16 表 4 岩石材料参数
Table 4. Rock material parameters
参数符号 参数解释说明 取值 参数符号 参数解释说明 取值 $ {\rho }_{0} $/(kg·m−3) 物质密度 2600 $ {p}_{\mathrm{crush}} $ 孔隙压实时压力 102 G/GPa 剪切模量 28.7 ${ {G}^{\mathrm{*} }_{\mathrm{c} } }$ 压缩屈服面参数 0.4 fc/MPa 单轴抗压强度 154 $ {{G}_{\mathrm{t}}}^{\mathrm{*}} $ 拉伸屈服面参数 0.7 $ N $ 孔隙度指数 0.697 $ {X}_{\mathrm{I}} $ 剪切模量缩减系数 0.5 $ {\beta }_{\mathrm{t}} $ 拉伸应变率指数 0.0115 $ {D}_{1} $ 初始损伤参数 0.04 $ {B}_{0} $ 状态方程参数 1.68 $ {D}_{2} $ 损伤参数 1 $ {B}_{1} $ 状态方程参数 1.68 $ {\beta }_{\mathrm{C}} $ 压缩应变率指数 0.0083 $ {\alpha }_{0} $ 初始孔隙度 1.0 $ {A}_{\mathrm{f}} $ 残余应力强度参数 1.62 T1 状态方程参数 30.64 $ {N}_{\mathrm{f}} $ 残余应力强度参数 0.6 表 5 炸药及其状态方程参数
Table 5. Explosive and its state equation parameters
密度/(kg·m−3) 爆速/(m·s−1) 压力/GPa JWL状态方程参数 $ {A}_{\mathrm{J}} $/GPa $ {B}_{\mathrm{J}} $/GPa R1 R2 $ \omega $ $ {E}_{\mathrm{J}} $/GPa 1320 6690 16 586 21.6 5.81 1.77 0.282 7.38 表 6 聚能管材料参数
Table 6. Shaped tube material parameters
ρ/(g·cm−3) γ C1/(km·s−1) S1 E/(GPa) Y/MPa Hc/MPa n Tm/K 2.790 2.00 5.330 1.340 27.6 265 426 0.34 775 注:$\rho $为红铜材料密度;$\gamma $为Grüneisen系数;${C_1}$为应变率硬化系数;$E$为弹性模量;${S_1}$、$Y$、${H_{\text{c}}}$为材料常数;$n$为应变硬化指数;${T_{\text{m}}}$为常态下材料的熔化温度; 表 7 炸药性能参数
Table 7. Explosive performance parameters
炸药类型 爆速/(m·s−1) 密度/(g·cm−3) 猛度/mm 殉爆距离/cm 震源药柱 3500 1.6 18 6 表 8 预裂爆破参数(
$H_1=12\;{\rm{m}} $ )Table 8. Pre-split blasting parameters (
$H_1=12\;{\rm{m}} $ )类型 直径/mm 倾角/(°) 长度/m 间距/m 填塞长度/m 线装药密度/(kg·m−1) 类型 板岩碎裂岩 120 65 14 1 3 0.5 普通 板岩碎裂岩 120 65 14 1.2 3 0.5 双线型聚能 白云岩 120 65 14 1.2 3 0.8 普通 白云岩 120 65 14 1.44 3 0.8 双线型聚能 -
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