Peak Elimination Effect of Radial Uncoupled Charge on Explosion Pressure and Its Influence on Rock Fracture Range

doi:10.12382/bgxb.2022.0431

Abstract

Abstract:

Understanding the law of rock fracture induced by single hole blasting is the basis to reveal the mechanism of rock fracture induced by multi-hole blasting. The mechanism of rock fracture induced by single hole blasting is clarified theoretically, and then the change process of stress, the propagation process of crack and the sizes of rock crushed zone and cracked zone with the decoupling coefficient of 1-3.5 are simulated by using a high explosive model and a rock RHT model. The laws of variation of the peak value of blasting pressure on the blast hole wall and the ranges of crushed zone and cracked zone with the increase in decoupling coefficient are analyzed. Calculated results show that the air-decoupling charge structure has about 2 times the peak shaving effect on the blasting pressure than the water-uncoupled charge structure due to the influences of different decoupling media. With the increase of decoupling coefficient from 1 to 3.5 (unchanged charge diameter), the diameters of crushed zone and cracked zone for the air-decoupling charge structure ranges from 4.44 to 1.59 and 22.5 to 7.62 times hole diameter, respectively. While for the water-decoupling charge structure, the diameters of crushed zone and the cracked zone are 4.44 to 2.74 times and 22.5 to 10.67 times more than hole diameter, respectively.

Key words: single hole blasting, rock breakage, decoupling coefficient, charge structure, crushed zone, cracked zone

CLC Number:

TD235.1

FAN Yong, WU Fan, LENG Zhengdong, YANG Guangdong, ZHAO Xiaohua. Peak Elimination Effect of Radial Uncoupled Charge on Explosion Pressure and Its Influence on Rock Fracture Range[J]. Acta Armamentarii, 2024, 45(1): 131-143.

Figures/Tables 16

Fig.1 Numerical model

Table 1 Explosive material parameters

A/GPa	B/GPa	R₁	R₂	ω	e₀/GPa	V
200	3.2	5.8	1.29	0.3	4.19	1.0

Table 2 Water material parameters

ρ_w/ (kg·m^-3)	C_w/ (m·s^-1)	μ_w	γ₀	a	S₁	S₂	S₃	E₀/ (J·kg^-1)
1000	0.148	8.9	0.493	0	2.55	1.986	0.227	0

Fig.2 Comparison between test and numericaly simulated results

Table 3 Parameters of RHT rock model

参数	数值	参数	数值
物质密度ρ_r/(kg·m^-3)	2660	失效面参数A	1.6
孔隙压缩时压力p_el/MPa	42.7	失效面指数N	0.61
孔隙度指数NP	3.0	压缩应变率相关指数BETAC	0.02
初始孔隙度α_o	1.6	拉伸应变率相关指数BETAT	0.05
Hugoniot多项式系数A₁/GPa	27.80	参考压缩应变率E0C	310^-5
Hugoniot多项式系数A₂/GPa	37.25	参考拉伸应变率E0T	3×10^-6
Hugoniot多项式系数A₃/GPa	21.32	破坏压缩应变率EC	3×10²⁵
EOS多项式参数B₀	1.22	破坏拉伸应变率ET	3×10²⁵
EOS多项式参数B₁	1.22	破坏参数D₁	0.015
EOS多项式参数T₁/GPa	27.8	破坏参数D₂	0.920
EOS多项式参数T₂	0	压缩屈服面参数GC^*	0.53
抗压强度f_c/MPa	200	拉伸屈服面参数GT^*	0.70
相对抗拉强度 $f t *$	0.05	最小损伤残余应变EPM	0.01
相对抗剪强度 $f s *$	0.27	残余应力强度参数AF	1.60
剪切模量G/GPa	18.36	残余应力强度指数AN	0.61
Mie-Gruneisen GAMMA	0	侵蚀塑性应变EPSF	2.0

Table 3 Parameters of RHT rock model

参数	数值	参数	数值
物质密度ρ_r/(kg·m^-3)	2660	失效面参数A	1.6
孔隙压缩时压力p_el/MPa	42.7	失效面指数N	0.61
孔隙度指数NP	3.0	压缩应变率相关指数BETAC	0.02
初始孔隙度α_o	1.6	拉伸应变率相关指数BETAT	0.05
Hugoniot多项式系数A₁/GPa	27.80	参考压缩应变率E0C	310^-5
Hugoniot多项式系数A₂/GPa	37.25	参考拉伸应变率E0T	3×10^-6
Hugoniot多项式系数A₃/GPa	21.32	破坏压缩应变率EC	3×10²⁵
EOS多项式参数B₀	1.22	破坏拉伸应变率ET	3×10²⁵
EOS多项式参数B₁	1.22	破坏参数D₁	0.015
EOS多项式参数T₁/GPa	27.8	破坏参数D₂	0.920
EOS多项式参数T₂	0	压缩屈服面参数GC^*	0.53
抗压强度f_c/MPa	200	拉伸屈服面参数GT^*	0.70
相对抗拉强度 $f t *$	0.05	最小损伤残余应变EPM	0.01
相对抗剪强度 $f s *$	0.27	残余应力强度参数AF	1.60
剪切模量G/GPa	18.36	残余应力强度指数AN	0.61
Mie-Gruneisen GAMMA	0	侵蚀塑性应变EPSF	2.0

Fig.3 Blasting pressure curves (air)

Fig.4 Stress curves

Fig.5 Dynamic propagation process of crack (air, decoupling coefficient is 2.0)

Fig.6 Rock cracking range induced by air-uncoupling charge (unchanged charge diameter)

Fig.7 Rock cracking range induced by air-uncoupling charge (unchanged hole diameter)

Fig.8 Blasting pressure curves (water)

Fig.9 Rock cracking range of water-uncoupling charge (unchanged charge diameter)

Fig.10 Rock cracking range of water-uncoupling charge (unchanged hole diameter)

Fig.11 Pressure peak curves

Fig.12 Variation of ratio of crushed zone and cracked zone to borehole diameter with decoupling coefficient

Fig.13 Comparison between simulated and theoretical values of range in crushed zone and cracked zone

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