岩石钻孔爆炸致裂研究

郭晓钧; 文鹤鸣

doi:10.11858/gywlxb.20210763

Borehole Blasting-Induced Fractures in Rocks

doi: 10.11858/gywlxb.20210763

GUO Xiaojun^1
,,
WEN Heming^{2,*
, ,}

1.
School of Civil Engineering and Architecture, Nanchang Hangkong University, Nanchang 330063, Jiangxi, China
2.
CAS Key Laboratory for Mechanical Behavior and Design of Materials, University of Science and Technology of China, Hefei 230027, Anhui, China

Funds: Doctoral Program of Nanchang Hangkong University (EA201511012)

More Information

Author Bio:
GUO Xiaojun (1982－), male, doctoral student, major in impact dynamics. E-mail: xjguo@mail.ustc.edu.cn

Corresponding author: WEN Heming (1965－), male, Ph.D, professor, major in impact dynamics. E-mail: hmwen@ustc.edu.cn

摘要

摘要: 岩石在爆炸载荷作用下的动态断裂行为得到了土木、岩石、采矿、石油和天然气等工业领域的关注。为此，研究了岩石钻孔的爆炸致裂问题。首先简单描述了岩石的动态本构模型，确定了花岗岩动态本构模型的参数；然后利用该模型对岩石钻孔爆炸致裂进行了数值模拟；最后将数值模拟结果与花岗岩钻孔爆炸实验结果进行比较。结果表明：数值模拟预测的峰值压力和开裂形貌与文献报道的柱形花岗岩实验观察结果吻合较好，并且数值模拟得出的开裂形貌还与方形花岗岩实验观察结果较一致；开裂形貌主要由拉伸应力造成，而钻孔周围的小裂纹主要由压缩/剪切应力造成。
- 花岗岩 /
- 本构模型 /
- 钻孔爆炸 /
- 开裂
Abstract: Dynamic fracture behavior of rocks under blasting loading are a major concern in civil engineering, mining, oil and gas industries. This study presented herein is on the borehole blasting-induced fractures in rocks. The paper consists of two parts: the first part gives a brief description of a constitutive model for rocks subjected to dynamic loading, which is mainly based on a recently developed model for concrete; the second part deals with numerical simulations of borehole blasting-induced fractures in rocks. The values of various parameters in the constitutive model for granite are first estimated and then employed in the numerical simulations. It is demonstrated that the numerical results in terms of peak pressures and crack patterns predicted from the present model are in good agreement with the experimental observations made both in cylindrical granite sample reported in the literature and in square granite specimens conducted in our own laboratory. Moreover, the analysis shows that the experimentally observed crack patterns are mainly caused by tensile stress, while the smaller cracks around borehole are created largely by compression/shear stress.
- granite rocks /
- constitutive model /
- borehole blasting /
- fracture

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Figure 1. Schematic diagram of EOS^[7]

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Figure 2. Schematic diagram of the residual strength surface for rock in total stress space

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Figure 3. Comparison of the strength surface between Eq.(6) (with B=2.59, N=0.66) and the triaxial test data for granite^[17]

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Figure 4. Tension dynamic increase factor obtained by Eq.(10) and the test results of various rocks at different strain rates^[18-23]

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Figure 5. Close-up view of the borehole region showing the material positions and the meshes

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Figure 6. Relation between the peak pressure and the distance from the borehole wall in granite

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Figure 7. Comparison of the crack patterns between the numerical prediction and the experiment of the cylindrical granite sample^[17]

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Figure 8. Numerically predicted crack pattern resulting from tension stress only

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Figure 9. Square granite sample

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Figure 10. Cross-section of the cylindrical RDX enclosed by an aluminum sheath

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Figure 11. Comparison of the crack patterns between the numerical prediction and the experiment with the square granite No.1 sample

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Figure 12. Comparison of the crack patterns between the numerical prediction andthe experiment with the square granite No.2 sample

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Table 1. Values of various parameters for granite^{[7, 15-17]}

p-$\alpha$ relation
${\,\rho {_0}}$/(kg∙m⁻³)	${p{_{ {\text{crush} } } }}$/MPa	${p{_{ {\text{lock} } } } }$/GPa	n	K₁/GPa	K₂/TPa	K₃/TPa
2660	50.5	3	3	25.7	−3	150

Strength surface					Strain rate effect
${f{_{\text{c} } } }'$/MPa	${f{_{\text{t} } }}$/MPa	B	N	G/GPa	${F{_{\text{m} }} }$	W_x
161.5	7.3	2.59	0.66	21.9	10	1.6

Strain rate effect			Shear damage
W_y	S	${\dot \varepsilon {_0}}$/s⁻¹	$\lambda{_\text{s}}$	$\lambda{_\text{m}}$	l	r
5.5	0.8	1.0	4.6	0.3	0.45	0.3

Lode effect			Tensile damage
e₁	e₂	e₃	c₁	c₂	$\varepsilon $_frac
0.65	0.01	5	3	6.93	0.007

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