Study and Analysis on Numerical Simulation of Empty Hole Effect Induced by Cutting Blasting

doi:10.12382/bgxb.2024.0250

Abstract

Abstract:

Cutting blasting plays a crucial role in achieving single-free-surface blasting during roadway excavation. To investigate the impact of empty holes on cutting blasting, the finite element method-smoothed particle hydrodynamics (FEM-SPH) coupling approach is used to establish a three-dimensional model of single empty hole cutting blasting based on the theory of empty hole action. The distribution characteristics of stress near the empty hole in multi-stage cutting blasting is analyzed, and the response laws of rock breaking, throwing, and cavity formation with respect to empty hole are studied. It is found that an empty hole guides the distribution of stress fields in the nearby rocks, the significant concentration effects of stress are generated around the empty hole. and the peak value area of stress is expanded, thereby providing the favorable conditions for subsequent blasting operations. there exists a strong correlation among rock throwing efficiency, empty hole and cavity size. Compared to the cases without an empty hole, the single empty hole cutting blasting exhibites a 34.7% increase in throwing speed and a 10.2% improvement in throwing efficiency. In field tests, cavity volume is increased by 17.1%, and the cutting depth is increased by 16.3%. However, there are no significant changes observed in overall cavity shape. These research findings provide partial theoretical support for designing and optimizing the actual cutting blasting parameters.

Key words: empty hole compensation, cutting blasting, finite element method-smoothed particle hydrodynamics, cavity-forming law, blasting experiment

CLC Number:

E951

TAO Zihao, LI Xianglong, HU Qiwen, WANG Jianguo. Study and Analysis on Numerical Simulation of Empty Hole Effect Induced by Cutting Blasting[J]. Acta Armamentarii, 2024, 45(12): 4246-4258.

Figures/Tables 23

Fig.1 Vertical cutting model and cavity formation process of empty hole

Fig.2 Stress concentration analysis of multiple holes

Fig.3 Redistribution of element stress near empty hole

Fig. 4 Connection and contact algorithm between SPH and FEM

Table 1 Material parameters of JHC constitutive model

参数	数值	参数	数值
ρ₀/(kg·m^-3)	2600	G/GPa	13.9
A	0.55	B	1.23
C	0.0097	N_p	0.76
f_c/MPa	65	T/MPa	4
EPS0	1×10^-5	EF_min	0.01
S_max/MPa	20	p_crush/MPa	20
μ_crush	0.00125	p_lock/MPa	30
μ_lock	0.174	K₁/GPa	39
D₁	0.04	K₂/GPa	-223
D₂	1	K₃/GPa	550
FS	1

Table 2 JWL model parameters

参数	数值	参数	数值
ρ₀/(kg·m^-3)	1100	p_cj /GPa	4.6
D/(m·s^-1)	4500	a/GPa	62.5
b/GPa	2.32	R₁	3.6
R₂	1.6	ω	0.41
E₀/GPa	3.15	V	1

Table 3 MAT_SOIL_AND_FOAM material parameters

参数	数值
γ_sat /(kN·m^-3)	17
G_s/MPa	2.524
K/MPa	4673
A₀~A₂/MPa	0.001,0.0049,0.0079
p_i/MPa	-0.005

Table 4 Pressure-strain values of soil

p/MPa	ln(V/V₀)	p/MPa	ln(V/V₀)
0	0	800	-0.1878
100	-0.0216	1000	-0.2408
200	-0.0437	2000	-0.5586
400	-0.0895	3000	-1.0272
600	-0.1374	4000	-1.9380

Fig.5 Numerical simulation verification

Fig.6 Cutting model layout and hole placement

Fig.7 Schematic diagram of the model section

Fig.8 Effective stress evolutions of the two models at different times

Fig.9 Selection of rock pressure feature points

Fig.10 Time history curves of pressures at feature points

Fig.11 Damage evolution process of models

Fig.12 Model cutting and throwing effect, and 3D groove cavity morphology

Fig.13 Full-section gun-hole layoutand cutting charge structure

Fig.14 Layout of gun holes

Table 5 Charge parameters of cutting blasting

炮孔类型	孔深/m	孔径/mm	炸药类型	装药类型	单孔装药量/kg		延期模式	延期时间/ ms
炮孔类型	孔深/m	孔径/mm	炸药类型	装药类型	孔号	药量	延期模式	延期时间/ ms
掏槽孔					1~4	9
辅助掏槽孔	3.2	50	1号岩石乳化炸药	连续装药	5~8	9	分段起爆	25
空孔		100

Table 6 Related parameters of explosives

药卷长度/ mm	药卷直径/ mm	单卷质量/ g	爆速 m/s	爆力值/ mL	猛度/ mm	殉爆距离/ cm
300	32	300	4500	320	16	4

Table 7 Comparison of test cavity size parameters

试验类型	掏槽类型	掏槽深度/m	槽腔口尺寸/m	槽腔体积/m³
现场试验	无空孔掏槽	1.59	1.17×1.12	1.81
	单空孔掏槽	1.85	1.21×1.19	2.12
数值模拟	无空孔掏槽	1.55	1.36×1.49	2.58
	单空孔掏槽	1.67	1.58×1.57	2.79

Fig.15 The effect and cavity shapes of two cutting arrangements after blasting

Fig.16 Comparative analysis of field test and simulated results

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