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过程工程学报 ›› 2021, Vol. 21 ›› Issue (7): 817-826.DOI: 10.12034/j.issn.1009-606X.220178

• 过程与工艺 • 上一篇    下一篇

结构异性煤体单轴/三轴冲击动力学性能研究

梁为民(), 刘恒, 李敏敏(), 岳高伟   

  1. 河南理工大学土木工程学院,河南 焦作 454000
  • 收稿日期:2020-06-09 修回日期:2020-08-10 出版日期:2021-07-28 发布日期:2021-07-27
  • 通讯作者: 李敏敏 Liangwmhpu@126.com;zhiyalmm@126.com
  • 作者简介:梁为民(1967-),男,河北省承德市人,博士,教授,主要从事爆破工程与岩土工程方面的教学和研究工作,E-mail: Liangwmhpu@126.com
    李敏敏,通讯联系人,E-mail: zhiyalmm@126.com.
  • 基金资助:
    国家自然科学基金资助项目(41772163)

Study on uniaxial/triaxial impact dynamic properties of structurally heterogeneous coal

Weimin LIANG(), Heng LIU, Minmin LI(), Gaowei YUE   

  1. School of Civil Engineering, Henan Polytechnic University, Jiaozuo, Henan 454000, China
  • Received:2020-06-09 Revised:2020-08-10 Online:2021-07-28 Published:2021-07-27
  • Contact: Minmin LI Liangwmhpu@126.com;zhiyalmm@126.com

摘要:

井下深孔爆破致裂是提高低渗煤层渗透率的重要措施之一,但由于煤层层理因素影响,在不同方向上的爆破致裂效果存在显著差异。采用分离式霍布金森压杆实验装置,对从垂直于层理方向和平行于层理方向进行取芯的煤样,分别进行冲击荷载为0.1, 0.15, 0.2, 0.3, 0.5 MPa的单/三轴SHPB冲击实验,分析结构异性煤体的冲击动力学性能。结果表明,煤样在不同冲击作用下,其单、三轴应力-应变曲线趋势相同,且其峰值应力、平均应变率随冲击荷载增大而增长趋势相同,其中峰值应力与冲击荷载符合指数关系,平均应变率与冲击荷载呈线性关系,相同冲击荷载下垂直于层理方向煤样的峰值应力、平均应变率相较于平行于层理方向煤样有所提升;进行三轴SHPB冲击时,在轴、围压对煤样约束作用下,其峰值应力、平均应变率相较于单轴情况下均有所提高,且在冲击荷载为0.15~0.2 MPa时峰值应力增幅最大,增大约50%,垂直于层理方向的动力学性能改变相较于平行于层理方向更明显。

关键词: 动力学性能, 分离式霍布金森压杆, 煤样, 层理方向, 应变率

Abstract:

As a heterogeneous, anisotropic and porous porous brittle material, the coal body has a large number of micro-scales such as bedding, joints, cracks, etc. so that the blasting and cracking effects in different directions will be significantly different. Based on this, a split Hopkinson pressure bar (SHPB) experimental device was used to perform impact loads of 0.1, 0.15, 0.2, 0.3, 0.5 MPa on the coal samples taken from the vertical and parallel bedding directions. The uniaxial/triaxial SHPB impact test was used to compare the uniaxial/triaxial impact dynamics performance of the anisotropic coal body stress-strain, peak stress, average strain rate, etc. after the impact. The results showed that under the action, the uniaxial and triaxial stress-strain curves had the same trend, and the peak stress and average strain rate increased with the impact load, and the growth trend was also the same. When the uniaxial impact, the stress of the coal sample followed the strain which can reach the peak stress quickly and dropped down quickly to complete the unloading. During triaxial impact, this stage was relatively smooth and had a longer elastoplastic deformation, so its dynamic mechanical properties were also improved well. Due to the relatively weak bonding surface between coal layers, the dynamic compressive strength was relatively smaller than the dynamic compressive strength in the vertical bedding direction; the triaxial SHPB impact had the peak stress and average strain rate under the constraint of the axial and confining pressures on the coal sample compared to the uniaxial improved, and the peak stress increased the most when the impact load was 0.15~0.2 MPa, increasing by about 50%. The dynamic performance improvement in the vertical bedding direction was slightly better than that in the parallel bedding direction. The effect of pressure had certain limitations, that was a certain confining pressure had a certain limit to improve the mechanical properties of coal samples.

Key words: dynamic performance, split Hopkinson pressure bar, coal sample, bedding direction, strain rate

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