On dynamic behaviors and failure of bedding coal rock subjected to cyclic impact
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摘要: 为研究复杂地况下含特征层理煤岩的动态力学行为,采用
∅ 50 mm分离式霍普金森压杆实验系统,对含层理 (0°、30°、45°、60°、90°)煤岩进行动态三轴循环冲击实验研究,并结合3D轮廓扫描仪量化其断裂界面,分析层理效应和围压效应对煤岩动态力学特性及其损伤破坏规律的影响。研究表明:围压的施加使煤岩应力-应变曲线出现弹性后效现象;较无围压状态,抗压强度提高3.9~4.2倍,失效应变增大2.59~3.05倍。随着层理角度的增大,煤岩的动态抗压强度、弹性模量和能量透射率均呈现先降低后升高的U形分布,在层理角为45°时均达到最小值;能量吸收率和断面粗糙度呈现先增大后减小的∩形分布,损伤变量呈现N形分布,在层理角为45°时达到最大值。煤岩的损伤破坏特征随层理角度的变化可概括为张拉破坏(0°)-剪切破坏(30°、45°和60°)-劈裂破坏(90°)的演变过程,所得特征规律可为实际复杂环境下煤层气资源安全高效开采提供理论支持。Abstract: Dynamic triaxial cyclic impact experiments on the coal rock samples with the bedding angles of 0°, 30°, 45°, 60°, and 90°, respectively, were conducted using a 50-mm split Hopkinson pressure bar (SHPB) system to study the dynamic mechanical behaviors of the coal rock with characteristic bedding under complex ground conditions. A 3D profile scanner was utilized to quantify the fracture interface roughness and to investigate the bedding effect on the dynamic fracture process of the coal rock. The bedding angle effect and confining pressure effect on the dynamic properties of the coal rock were explored by combining dynamic parameters such as compressive strength, elastic modulus, energy distribution evolution with the fracture surface roughness variation. The research shows that when confining pressure is applied, the stress-strain curve of the coal rock has an elastic aftereffect. The dynamic compressive strength and failure strain of the bedding coal rock with confining pressure are respectively 3.9−4.2 and 2.59−3.05 times higher than those without confining pressure. As the bedding angle increases, the dynamic compressive strength, elastic modulus, and energy transmitted ratio of the coal rock display the U-shaped distribution, which decreases first and then increases, reaching the minimum at the bedding angle of 45°. Meanwhile, the energy absorbed ratio and fracture surface roughness show the ∩-shaped distribution, first increasing and then decreasing, and the damage variable shows the N-shaped distribution, reaching the maximum at the bedding angle of 45°. The failure of the coal rock with 45° bedding is the most serious, which is more prone to intergranular and spalling fractures. However, the 90° bedding coal rock is more likely to absorb energy and to form transgranular fractures, resulting in a large number of mesoscopic fractures. Variation of the damage characteristics of the coal rocks with bedding angle can be summarized as a tensile damage (0°)-shear damage (30°, 45°, 60°)-splitting damage (90°) evolution process. The relevant characteristic results obtained from the experiments can provide a theoretical support for the safe and efficient exploitation of coalbed methane resources in the complex environment under practical working conditions. -
聚氨酯泡沫材料是一种密度小、价格低、成形容易的多孔介质, 具有很好的吸收动能特性, 是一种理想的缓冲吸能材料[1]。硬质聚氨酯泡沫的泡孔以闭孔为主, 具有极低的导热系数、较低的密度、一定的强度和硬度, 电学性能、隔声抗震效果优良, 经过添加剂处理, 又能提高阻燃性、耐水性、耐腐蚀性, 广泛应用于汽车、建筑、造船等行业。在防护工程设计中, 通常用硬质聚氨酯与钢板构成复合结构来抵御武器爆炸的打击, 这种钢夹芯结构能够缓和冲击、减弱振荡、降低应力幅值, 可以作为舰船的防护结构以提高其生存能力[2]。
本文中应用有限元方法, 对聚氨酯泡沫夹芯结构在空气中TNT爆炸的动力学响应进行数值模拟, 分析聚氨酯泡沫材料在整体结构中起的作用, 并与相同面密度的钢板进行对比研究, 以验证聚氨酯泡沫夹芯结构良好的抗爆吸能特性。
1. 爆炸波在空气中的传播
TNT在空气中爆炸时, 在有限的空间中迅速释放出大量的能量, 导致爆炸气体生成物的压力和温度局部上升, 使其周围介质受到高温高压爆炸产物的作用。根据爆轰理论, 爆炸产物向某一介质中飞散时, 在飞散的瞬间, 该介质中必然产生冲击波[3-4]。典型的理想气体中爆炸波的传播过程如图 1所示。
在ta时刻, 空气中某一点的压强瞬间达到峰值超压pI(与大气压p0的差值), 经过时间t+, 压力很快衰减到大气压强p0, 然后继续减小形成稀疏区, 在时刻ta+t++t-时, 压力回到大气压强。pI是峰值超静压[5], 理想空气中波的传播规律可由改进后的Friedlander经验公式描述[6]:
p(t)=p0+pI(1−tt+)e−a(tt+) (1) 式中:t+是正相持续时间, 指数衰减因子a是一个与峰值超压值有关的经验常数。
2. 数值计算模型
利用Ansys/Autodyn非线性有限元计算程序的多物质欧拉求解器来计算TNT在空气中的自由爆炸过程。Autodyn程序采用有限差分以及有限体积法为主的流体数值计算方法, 采用人工黏性算法来抹平物理场中的强间断, 可以很好地模拟爆炸后压力波的传播规律。
2.1 模型描述
如图 2所示, 采用二维轴对称模型。聚氨酯/钢夹芯结构为直径200 mm、厚14 mm的圆板, 其中上下面板的厚度为2 mm, 中间聚氨酯芯体的厚度为10 mm。炸药TNT半径为10 mm, 爆距R=100 mm。将整个模型放到空气环境中去。空气采用Euler单元算法, 夹芯结构采用Lagrange单元算法, 采用流固耦合算法将聚氨酯/钢夹芯结构耦合到空气当中去。
2.2 材料模型
空气采用理想气体模型, 其性能一般采用线性多项式的状态方程来描述, 其Gama形式为[7]:
p=(γ−1)ρρ0E (2) 式中:p为气体压力, γ是比热比, ρ表示空气的当前密度, ρ0是初始时刻的空气密度, E为气体单位体积的内能。计算中, 指定空气的比内能E=206.8 kJ/kg(一个大气压强)。
对于TNT炸药, 一般采用JWL状态方程来描述炸药爆轰过程中压力和内能及其相对体积的关系[8]:
p=A(1−ωR1V)e−R1V+B(1−ωR2V)e−R2V+ωEV (3) 式中:p为爆炸产生的压力; V为单位体积装药产生的爆轰产物的体积, 即压力为p时的体积与初始体积的比值; E是爆轰产物的体积内能; A、B、R1、R2均为状态方程参数。
钢(Steel 3430)的本构方程采用Johnson-Cook来描述[7]:
σ=(A+Bεnp)[1+Cln(˙εp˙ε0)][1−(T−TrefTm−Tref)m] (4) 式中:σ为Von Mises等效流变应力; 屈服极限A=792 MPa; B为加工硬化模量; n为硬化系数; 应变速率常数C=0.014, 热软化常数
p为等效塑性应变率,
0为应变速率参考值; Tref为温度参考值; Tm为材料熔化温度。
聚氨酯泡沫材料采用线弹性本构模型和线性状态方程[9]:
P=Kμ (5) 式中:μ=(ρ/ρ0)-1, K是材料的体积模量。
2.3 接触设置
面板与芯体之间采用Lagrange/Lagrange Interaction接触。夹芯结构与空气之间采用Euler/Lagrange interaction流固耦合接触, 这样夹芯结构的整个外表面自动和空气单元接触, 空气单元施加压力给夹芯结构单元, 可以通过对夹芯结构表面进行积分得到节点力, 同时, 夹芯结构对于空气的作用相当于施加了流动约束, 并且两者之间不考虑摩擦效应, 部分覆盖的网格会被自动合并。
2.4 边界条件
为了模拟无限域中聚氨酯/钢夹芯结构的动力学响应, 空气Euler单元采用Flow_out流体边界条件, 用来模拟空气自由面, 从而达到模拟空气无限大域的目的。夹芯结构Lagrange单元采用两端固支边界条件。
3. 数值计算结果分析
为了提高计算精度和计算效率, 对爆炸波在空气中的传播过程采用一维轴对称模型计算, 利用Autodyn的Remapping功能将一维计算结果映射到二维轴对称模型中去。
3.1 空气中爆炸波的传播过程
某时刻空气中压强分布如图 3所示。对空气中不同爆距设置观测点, 得到其压力时程如图 4所示。
为了说明空气中爆炸波传播的数值模拟精度, 将计算结果与Henrych(1979)给出的空气中冲击波峰值超压计算经验公式[10]对比:
p1={1.4072Z+0.554Z2−0.0357Z3+0.000625Z40.05≤Z<0.30.619Z−0.033Z2+0.213Z30.3≤Z<1.00.066Z+0.405Z2+0.329Z31.0≤Z<10 (6) 式中:pI为冲击波峰值超压, Z=R·W-1/3为比例距离, R为测点与爆心之间的距离, W为TNT药量。图 5是数值计算结果与经验公式的比较。可以看出, 数值模拟与经验公式结果比较一致, 当爆距较小时, Z值太小会引起经验公式计算结果偏差较大。
3.2 夹芯结构动力学响应分析
当空气中的爆炸波达到夹芯结构, 引起夹芯结构的动态响应过程。图 6是不同时刻前后面板的Mises应力云图。
图 7是前后面板离中心点不同距离的竖向速度时程图。当爆炸波传递到夹芯结构上面板后, 上面板的最大速度在0.38 ms时刻为15.4 m/s, 下面板的最大速度出现在0.32 ms, 为15.0 m/s, 前后板的最大速度很接近。从图中可以看出, 前后面板不同点的速度呈震荡规律变化, 其原因是因为夹芯层聚氨酯起的缓冲作用。通过压力波的传递, 聚氨酯将前面板的能量传递到后面板, 从而使前面板的速度减小, 后面板的速度增大, 反之亦然。压力波在夹芯结构之间反复传递, 可以看出聚氨酯泡沫层很好的缓冲作用, 对保护结构起很大的作用。
图 8是前后面板中心点的加速度时程图。从图中看出, 前面板加速度幅值逐渐增大到1 897 m/s2, 后面板的加速度幅值逐渐增大到1 568 m/s2, 并且前面板的加速度幅值大于后面板加速度的幅值。随后加速度幅值均减小, 0.3 ms时前后面板的加速度幅值均达到最小, 随后, 前后面板中心点加速度幅值逐渐增大, 而且后面板的幅值略大于前面板的幅值。
对前后面板离中心点不同距离的挠度进行分析, 如图 9所示。后面板靠近中心点范围内的挠度值大于前面板。例如, 前后面板距离中心点20 mm处的挠度分别为2.1、2.6 mm, 远离中心点的挠度大致相同。值得指出的是, 在0.2~0.28 ms内, 板上最大挠度并没有发生在中心点。
3.3 夹芯结构吸能特性分析
作为泡沫材料, 聚氨酯具有很好的吸能特性。图 10是不同材料在爆炸过程中吸能对比曲线。对聚氨酯夹芯结构分析, 聚氨酯泡沫芯体吸收的能量为31 J, 前后面板吸收的能量为73 J。在结构中, 聚氨酯芯体质量所占的比重为27%, 吸收的能量占夹芯结构吸收总能量的30%。这表明作为泡沫材料, 聚氨酯具有较高的吸能效率。将夹芯结构与相同面密度的5.6 mm钢板进行比较分析可知, 相同面密度的钢板吸收的能量为70 J, 加入聚氨酯泡沫芯体后, 夹芯结构的吸收能量为相同面密度钢板的1.49倍, 大大提高了结构的吸能能力。
4. 结论
利用Ansys/Autodyn非线性有限元程序对聚氨酯/钢夹芯结构在TNT空气爆炸后的动力学响应进行了研究。数值结果并结合经验公式表明:
(1) 用Autodyn模拟TNT在空气中爆炸后波的传播规律精度很高, 说明本文数值模拟结果可信。
(2) 在爆炸载荷作用下, 前后面板的竖向速度成震荡规律变化, 主要是由于聚氨酯泡沫芯体起的缓冲作用。前后面板中心点加速度幅值先增大后减小, 然后又增大。并且在0.3 ms前, 前面板中心点的加速度幅值略大于后面板的中心点加速度幅值, 在0.3 ms后, 后面板中心点的加速度幅值略大于前面板中心点的加速度幅值。
(3) 在吸收能量方面, 质量占27%的聚氨酯芯体吸收的能量占夹芯结构整体结构的30%, 聚氨酯泡沫具有较高的吸能效率。与相同面密度的钢板比较可得, 加入聚氨酯芯体后, 结构的吸收能量为相同面密度钢板的1.49倍。说明聚氨酯/钢夹芯结构具有良好的吸能性能, 可以设计成不同的结构形式以获得良好的抗爆性能。
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[1] 叶建平, 史保生, 张春才. 中国煤储层渗透性及其主要影响因素 [J]. 煤炭学报, 1999, 24(2): 8–12. DOI: 10.3321/j.issn:0253-9993.1999.02.002.YE J P, SHI B S, ZHANG C C. Coal reservoir permeability and its controlled factors in China [J]. Journal of China Coal Society, 1999, 24(2): 8–12. DOI: 10.3321/j.issn:0253-9993.1999.02.002. [2] MOORE T A. Coalbed methane: a review [J]. International Journal of Coal Geology, 2012, 101: 36–81. DOI: 10.1016/j.coal.2012.05.011. [3] HAMAWAND I, YUSAF T, HAMAWAND S G. Coal seam gas and associated water: a review paper [J]. Renewable and Sustainable Energy Reviews, 2013, 22: 550–560. DOI: 10.1016/j.rser.2013.02.030. [4] WANG D K, LV R H, WEI J P, et al. An experimental study of the anisotropic permeability rule of coal containing gas [J]. Journal of Natural Gas Science and Engineering, 2018, 53: 67–73. DOI: 10.1016/j.jngse.2018.02.026. [5] 傅雪海, 秦勇, 张万红, 等. 基于煤层气运移的煤孔隙分形分类及自然分类研究 [J]. 科学通报, 2005, 50(S1): 66–71. DOI: 10.3321/j.issn:0023-074X.2005.z1.009.FU X H, QIN Y, ZHANG W H, et al. Fractal classification and natural classification of coal pore structure based on migration of coal bed methane [J]. Chinese Science Bulletin, 2005, 50(S1): 66–71. DOI: 10.3321/j.issn:0023-074X.2005.z1.009. [6] LI B B, YANG K, XU P, et al. An experimental study on permeability characteristics of coal with slippage and temperature effects [J]. Journal of Petroleum Science and Engineering, 2019, 175: 294–302. DOI: 10.1016/j.petrol.2018.12.048. [7] 吴飞鹏, 刘洪志, 任杨, 等. 燃爆冲击作用下岩石初始破坏区形成机制与主控因素 [J]. 爆炸与冲击, 2016, 36(5): 663–669. DOI: 10.11883/1001-1455(2016)05-0663-07.WU F P, LIU Z H, REN Y, et al. Formation mechanism and main controlling factors of rock’s initial damaged zone under explosive impact effect [J]. Explosion and Shock Waves, 2016, 36(5): 663–669. DOI: 10.11883/1001-1455(2016)05-0663-07. [8] 牟恭雨, 罗宁, 申涛, 等. 聚能射流侵彻页岩储层损伤裂隙形成机制[J]. 爆炸与冲击, 2023, 43(3): 033301. DOI: 10.11883/bzycj-2022-0182.MU G Y, LUO N, SHEN T, et al. Mechanism of damage-induced fracture formation in shale reservoir penetrated by shaped charge jet [J]. Explosion and Shock Waves, 2023, 43(3): 033301. DOI: 10.11883/bzycj-2022-0182. [9] RAMULU M, CHAKRABORTY A K, SITHARAM T G. Damage assessment of basaltic rock mass due to repeated blasting in a railway tunnelling project-A case study [J]. Tunnelling and Underground Space Technology, 2009, 24(2): 208–221. DOI: 10.1016/j.tust.2008.08.002. [10] LI H B, XIA X, LI J C, et al. Rock damage control in bedrock blasting excavation for a nuclear power plant [J]. International Journal of Rock Mechanics and Mining Sciences, 2011, 48(2): 210–218. DOI: 10.1016/j.ijrmms.2010.11.016. [11] 谢和平. 深部岩体力学与开采理论研究进展 [J]. 煤炭学报, 2019, 44(5): 1283–1305. DOI: 10.13225/j.cnki.jccs.2019.6038.XIE H P. Research review of the state key research development program of China: deep rock mechanics and mining theory [J]. Journal of China Coal Society, 2019, 44(5): 1283–1305. DOI: 10.13225/j.cnki.jccs.2019.6038. [12] 鞠杨, 李业学, 谢和平, 等. 节理岩石的应力波动与能量耗散 [J]. 岩石力学与工程学报, 2006, 25(12): 2426–2434. DOI: 10.3321/j.issn:1000-6915.2006.12.007.JU Y, LI Y X, XIE H P, et al. Stress wave propagation and energy dissipation in jointed rocks [J]. Chinese Journal of Rock Mechanics and Engineering, 2006, 25(12): 2426–2434. DOI: 10.3321/j.issn:1000-6915.2006.12.007. [13] MA Y, PAN Z J, ZHONG N N, et al. Experimental study of anisotropic gas permeability and its relationship with fracture structure of Longmaxi Shales, Sichuan Basin, China [J]. Fuel, 2016, 180: 106–115. DOI: 10.1016/j.fuel.2016.04.029. [14] TAN Y L, PAN Z J, LIU J S, et al. Experimental study of permeability and its anisotropy for shale fracture supported with proppant [J]. Journal of Natural Gas Science and Engineering, 2017, 44: 250–264. DOI: 10.1016/j.jngse.2017.04.020. [15] ZHAO Y X, ZHAO G F, JIANG Y D, et al. Effects of bedding on the dynamic indirect tensile strength of coal: laboratory experiments and numerical simulation [J]. International Journal of Coal Geology, 2014, 132: 81–93. DOI: 10.1016/j.coal.2014.08.007. [16] KONG X G, WANG E Y, LI S G, et al. Dynamic mechanical characteristics and fracture mechanism of gas-bearing coal based on SHPB experiments [J]. Theoretical and Applied Fracture Mechanics, 2020, 105: 102395. DOI: 10.1016/j.tafmec.2019.102395. [17] HAO X J, DU W S, ZHAO Y X, et al. Dynamic tensile behaviour and crack propagation of coal under coupled static-dynamic loading [J]. International Journal of Mining Science and Technology, 2020, 30(5): 659–668. DOI: 10.1016/j.ijmst.2020.06.007. [18] LIU X H, DAI F, ZHANG R, et al. Static and dynamic uniaxial compression tests on coal rock considering the bedding directivity [J]. Environmental Earth Sciences, 2015, 73(10): 5933–5949. DOI: 10.1007/s12665-015-4106-3. [19] CHEN Y L, ZHANG Y N, LI X L. Experimental study on influence of bedding angle on gas permeability in coal [J]. Journal of Petroleum Science and Engineering, 2019, 179: 173–179. DOI: 10.1016/j.petrol.2019.04.010. [20] ZHAO Y X, GONG S, HAO X J, et al. Effects of loading rate and bedding on the dynamic fracture toughness of coal: laboratory experiments [J]. Engineering Fracture Mechanics, 2017, 178: 375–391. DOI: 10.1016/j.engfracmech.2017.03.011. [21] WANG W, ZHAO Y X, TENG T, et al. Influence of bedding planes on mode Ⅰ and mixed-mode (Ⅰ-Ⅱ) dynamic fracture toughness of coal: analysis of experiments [J]. Rock Mechanics and Rock Engineering, 2021, 54(1): 173–189. DOI: 10.1007/s00603-020-02250-9. [22] FAN X R, LUO N, LIANG H L, et al. Dynamic breakage characteristics of shale with different bedding angles under the different ambient temperatures [J]. Rock Mechanics and Rock Engineering, 2021, 54(6): 3245–3261. DOI: 10.1007/s00603-021-02463-6. [23] 王卫华, 李夕兵, 左宇军. 非线性法向变形节理对弹性纵波传播的影响 [J]. 岩石力学与工程学报, 2006, 25(6): 1218–1225. DOI: 10.3321/j.issn:1000-6915.2006.06.020.WANG W H, LI X B, ZUO Y J. Effects of single joint with nonlinear normal deformation on P-wave propagation [J]. Chinese Journal of Rock Mechanics and Engineering, 2006, 25(6): 1218–1225. DOI: 10.3321/j.issn:1000-6915.2006.06.020. [24] 李业学, 谢和平, 朱哲明, 等. 应力波穿越分形节理时的透反射规律研究 [J]. 岩石力学与工程学报, 2009, 28(1): 120–129. DOI: 10.3321/j.issn:1000-6915.2009.01.016.LI Y X, XIE H P, ZHU Z M, et al. Study on rules of transmission and reflection of stress wave across fractal joint [J]. Chinese Journal of Rock Mechanics and Engineering, 2009, 28(1): 120–129. DOI: 10.3321/j.issn:1000-6915.2009.01.016. [25] 许金余, 范建设, 吕晓聪. 围压条件下岩石的动态力学特性 [M]. 西安: 西北工业大学出版社, 2012: 21–25.XU J Y, FAN J S, LYU X C. Dynamic mechanical properties of rock with the confining pressure [M]. Xi’an: Northwestern Polytechnical University Press, 2012: 21–25. [26] LEWANDOWSKI C M, COINVESTIGATOR N. Split Hopkinson (Kolsky) bar: design, testing and applications [M]. Springer, 2015: 6–12. [27] FAKHIMI A, AZHDARI P, KIMBERLEY J. Physical and numerical evaluation of rock strength in Split Hopkinson Pressure Bar testing [J]. Computers and Geotechnics, 2018, 102: 1–11. DOI: 10.1016/j.compgeo.2018.05.009. [28] FENG J J, WANG E Y, CHEN X, et al. Energy dissipation rate: an indicator of coal deformation and failure under static and dynamic compressive loads [J]. International Journal of Mining Science and Technology, 2018, 28(3): 397–406. DOI: 10.1016/j.ijmst.2017.11.006. [29] LUO N, SUO Y C, FAN X R, et al. Research on confining pressure effect of pore structure of coal-rich in coalbed methane under cyclic impact [J]. Energy Reports, 2022, 8: 7336–7348. DOI: 10.1016/j.egyr.2022.05.238. [30] SUO Y C, LUO N, CHAI Y B, et al. Experimental investigation of dynamic mechanical characteristics of inhomogeneous composite coal-sandstone combination for coalbed methane development [J]. Heliyon, 2022, 8: e11628. DOI: 10.1016/j.heliyon.2022.e11628. [31] 谢和平, 彭瑞东, 鞠杨, 等. 岩石破坏的能量分析初探 [J]. 岩石力学与工程学报, 2005, 24(15): 2603–2608. DOI: 10.3321/j.issn:1000-6915.2005.15.001.XIE H P, PENG R D, JU Y, et al. On energy analysis of rock failure [J]. Chinese Journal of Rock Mechanics and Engineering, 2005, 24(15): 2603–2608. DOI: 10.3321/j.issn:1000-6915.2005.15.001. [32] 谢和平, 鞠杨, 黎立云. 基于能量耗散与释放原理的岩石强度与整体破坏准则 [J]. 岩石力学与工程学报, 2005, 24(17): 3003–3010. DOI: 10.3321/j.issn:1000-6915.2005.17.001.XIE H P, JU, Y, LI L Y. Criteria for strength and structural failure of rocks based on energy dissipation and energy release principles [J]. Chinese Journal of Rock Mechanics and Engineering, 2005, 24(17): 3003–3010. DOI: 10.3321/j.issn:1000-6915.2005.17.001. [33] 黎立云, 徐志强, 谢和平, 等. 不同冲击速度下岩石破坏能量规律的实验研究 [J]. 煤炭学报, 2011, 36(12): 2007–2011. DOI: 10.13225/j.cnki.jccs.2011.12.012.LI L Y, XU Z Q, XIE H P, et al. Failure experimental study on energy laws of rock under differential dynamic impact velocities [J]. Journal of China Coal Society, 2011, 36(12): 2007–2011. DOI: 10.13225/j.cnki.jccs.2011.12.012. [34] 刘晓辉, 薛洋, 周济芳, 等. 层理煤岩动态破坏能量变化规律及损伤特征 [J]. 地下空间与工程学报, 2021, 17(4): 1052–1062.LIU X H, XUE Y, ZHOU J F, et al. Dynamic failure energy change and damage characteristics of bedding coal rock [J]. Chinese Journal of Underground Space and Engineering, 2021, 17(4): 1052–1062. [35] 周磊, 姜亚成, 朱哲明, 等. 动载荷作用下裂隙岩体的止裂机理分析 [J]. 爆炸与冲击, 2021, 41(5): 053102. DOI: 10.11883/bzycj-2020-0125.ZHOU L, JIANG Y C, ZHU Z M, et al. Mechanism study of preventing crack propagation of fractured rock under dynamic loads [J]. Explosion and Shock Waves, 2021, 41(5): 053102. DOI: 10.11883/bzycj-2020-0125. [36] 杨国梁, 毕京九, 郭伟民, 等. 加载角度对层理页岩裂纹扩展影响的实验研究 [J]. 爆炸与冲击, 2021, 41(9): 093101. DOI: 10.11883/bzycj-2021-0097.YANG G L, BI J J, GUO W M, et al. Experimental study on the effect of loading angle on crack propagation in bedding shale [J]. Explosion and Shock Waves, 2021, 41(9): 093101. DOI: 10.11883/bzycj-2021-0097. -