Dynamic response mechanism of a rock-filling interfacial coupling body to blasting in it
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摘要: 充填采矿法的充填体与矿岩体构成的界面耦合结构体,受采矿爆破影响会持续受到动力扰动,在充-岩界面耦合处易产生脱粘、裂隙扩展等行为,为井下生产带来安全隐患。采用ANSYS/LS-DYNA建立了充-岩界面耦合体模型,分析了爆破作用对界面耦合体结构的力学影响,获取了不同界面粗糙度、充填体养护龄期和起爆方式等因素对爆破裂隙扩展及应力波峰值应力的影响,探讨了爆破动力作用机理。结果表明:(1)爆破冲击在界面耦合体中存在拉、压和剪3种力学作用,且随着界面粗糙度的提高,界面受力呈先上升后下降趋势;(2)随着充填体养护时间增长,界面破坏逐步从受拉转化成剪切损伤;(3)同时起爆对耦合界面的损伤比逐孔起爆的小。Abstract: The interfacial coupling structure between the backfill and ore rock body in the filling mining method will be continuously disturbed by the influence of mining and blasting. In the filling-rock interfacial coupling, it is easy to produce the behaviors of debonding and fissure expansion, which will bring potential safety hazards to underground production. Because the field experiment is time-consuming and laborious, and it is difficult to observe the impact effect and the rock crack propagation process when the explosive is detonated, the simulation method was adopted for research. In the simulation, reasonable simplification is particularly important. According to the actual situation of blasting hole layout, the three rows of blasting holes that were detonated at one time were simplified into a single-row blasting hole model and an edge blasting hole model. According to the research results in related literatures, the coupling surfaces of the filling bodies and the ore rocks were simplified into three kinds (a flat interface, wavy interface and serrated interface). The three different shapes of the interfaces correspond to the different roughnesses of the interfaces, respectively. By considering that the hole arrangement method used in stope blasting is vertical hole arrangement, the holes are parallel, and at the same time, in order to improve the calculation of the software efficiency, simplified the three-dimensional model of the stope into a two-dimensional plane model. After a series of simplifications, a physical model for the filling-rock interface coupling body was proposed, and the corresponding geometric analysis model was established by using the ANSYS/LS-DYNA software And different material parameters were assigned to the different parts of the model, and the blasting effect was analyzed by software calculation. The mechanical influence of the interface coupling body structure was obtained, and the response law of different interface roughness, the curing age of the filling body and the blasting method on the blasting shock was obtained, and the mechanism of the blasting dynamics was discussed. The research results can reveal mechanical behaviors such as debonding and crack propagation at the coupling of filling-rock interface, and clarify the influence of different factors on the law of blasting shock response and the mechanism of blasting dynamics, which has certain guiding significance for downhole safety production. The results show as follows. (1) The blasting impact has three mechanical effects in the interface coupling body: tension, pressure and shear. When the stress wave passes through the interface, the peak acceleration of the monitoring point at the interface will increase due to different degrees of refraction. After passing through the coupling interface, the stress wave energy decays rapidly. (2) The impact of different interface roughness on blasting action is different. The joint roughness coefficient (JRC) represents the roughness of the interface coupling body. With the increase of the JRC value, the interface stress tends to rise first and then decline, but the overall damage decreases. (3) As the curing time of the backfill increases, the fracture range at the coupling interface shrinks, and the interface damage gradually changes from tensile damage to shear damage. (4) The damage of different detonation modes to the interface coupling body is different, and the damage of simultaneous detonation to the coupling interface is weaker than that of hole-by-hole detonation.
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Key words:
- coupling structure /
- explosive impact /
- dynamic disturbance /
- crack propagation
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表 1 炮孔布置参数
Table 1. Parameters of blasting hole arrangement
布置方式 炸药密度/(kg·m−3) 孔径/mm 孔深/m 炮孔排距/m 炮孔间距/m 垂直中深孔 1060 90 8 2 2 表 2 耦合界面形态及对应节理粗糙度
Table 2. Coupling interface morphologies and the corresponding joint roughness coefficients
耦合界面类别 剖面线形态 $ {c}_{\rm{jr}} $ 平直形 0 波浪形 8.12 锯齿形 18.38 表 3 炸药材料及JWL状态方程参数
Table 3. Parameters for explosive materials and JWL equation of state
密度/(kg·m−3) 爆速/(km·s−1) A/GPa B/GPa R1 R2 ω E/GPa 1 060 4 220 0.2 4.5 1.1 0.35 4.2 表 4 岩石和充填体材料参数
Table 4. Parameters for rocks and filling materials
材料 密度/(kg·m−3) 泊松比 弹性模量/GPa 单轴抗压强度/GPa 岩石 2 551 0.25 25.00 100.00 7 d龄期充填体 2 180 0.31 0.92 2.10 28 d龄期充填体 2 200 0.24 2.20 4.17 表 5 不同粗糙度界面耦合体监测点1~4峰值拉应力
Table 5. Peak tensile stress at monitoring points 1−4 in the interface coupling bodies with different roughnesses
监测点编号 单排炮孔峰值拉应力/MPa 两帮炮孔峰值拉应力/MPa $ {c}_{\rm{jr}} $=0 $ {c}_{\rm{jr}} $=8 $ {c}_{\rm{jr}} $=20 $ {c}_{\rm{jr}} $=0 $ {c}_{\rm{jr}} $=8 $ {c}_{\rm{jr}} $=20 1 9.96 3.06 2.56 0.73 4.76 0.73 2 0 2.85 0.04 0.90 4.46 0.04 3 0 9.17×10−3 0.02 3.73×10−3 0.01 0.02 4 0 9.61×10−3 0.01 4.86×10−3 0.02 0.02 表 6 不同龄期界面耦合体监测点1~4峰值拉应力
Table 6. Peak tensile stress at monitoring points 1−4 in different-age interface coupling bodies
监测点编号 单排炮孔峰值拉应力/MPa 两帮炮孔峰值拉应力/MPa 7 d龄期 28 d龄期 7 d龄期 28 d龄期 1 9.96 3.12 0.73 0.70 2 1.15×10-3 2.10×10-3 0.90 0.97 3 1.43×10-3 0.03 3.73×10-3 0.56 4 9.56×10-4 0.02 4.86×10-3 0.26 表 7 不同起爆方式下界面耦合体监测点1~4峰值拉应力
Table 7. Peak tensile stress at monitoring points 1−4 in interfacial coupling bodies with different detonation modes
监测点编号 单排炮孔峰值拉应力/MPa 两帮炮孔峰值拉应力/MPa 同时起爆 逐孔起爆 同时起爆 逐孔起爆 1 9.96 2.66 0.73 14.64 2 0 0.09 0.90 2.34 3 0 0.05 3.73×10−3 0.19 4 0 0.04 4.86×10−3 0.16 -
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