郑建伟,王书文,李海涛,等. 层面数量对煤岩组合体抗压特性影响的实验研究[J]. 煤田地质与勘探,2023,51(5):11−22. DOI: 10.12363/issn.1001-1986.22.10.0787
引用本文: 郑建伟,王书文,李海涛,等. 层面数量对煤岩组合体抗压特性影响的实验研究[J]. 煤田地质与勘探,2023,51(5):11−22. DOI: 10.12363/issn.1001-1986.22.10.0787
ZHENG Jianwei,WANG Shuwen,LI Haitao,et al. Experimental study on compressive strength characteristics of coal-rock combinations influenced by number of bedding surfaces[J]. Coal Geology & Exploration,2023,51(5):11−22. DOI: 10.12363/issn.1001-1986.22.10.0787
Citation: ZHENG Jianwei,WANG Shuwen,LI Haitao,et al. Experimental study on compressive strength characteristics of coal-rock combinations influenced by number of bedding surfaces[J]. Coal Geology & Exploration,2023,51(5):11−22. DOI: 10.12363/issn.1001-1986.22.10.0787

层面数量对煤岩组合体抗压特性影响的实验研究

Experimental study on compressive strength characteristics of coal-rock combinations influenced by number of bedding surfaces

  • 摘要: 煤层顶板分层特征对于煤岩系统的力学行为有重要影响,将其简化为具有岩石单元内含有不同层面数量的煤岩组合体,并开展单轴压缩实验。借助应力监测系统、DIC和声发射系统采集并分析实验过程中的应力−应变特征、表面应变场演变规律、声发射特性。实验表明:煤岩组合体的应力−应变过程可以分为裂隙压密阶段、“线性”增加阶段、非稳定破裂阶段和峰后阶段4个阶段,煤体单元首先发生渐进式的破坏,其过程为煤块弹射−煤块与组合体剥离−剥离状的煤块弹射−倾倒破坏。结合声发射特征可以认为单轴压缩过程中煤岩组合体具有更加明显的压密现象、小台阶现象和峰后应力增减现象,主要是组合体的非均质程度相对增加,内部不能协同变形所导致的。组合体内“煤−岩”层面处会出现明显的应变集中现象,主要是因为该处材料的物理力学性质差异较大,且层面处粘黏剂的存在会导致横向约束作用,岩石单元由单向受压转变为三向压拉状态,煤体单元由单向受压转变为三向受压状态,因此,“煤−岩”层面处更容易发生破坏,此处的声发射信号相对集中,更易形成应变集中。研究认为煤岩组合体中岩石单元层面数量的增加,其等效弹性模量降低、整体性弱化和承载能力下降,组合体单轴压缩强度有降低的趋势。研究成果可以为巷道冲击地压等动力灾害的防治提供一定的指导。

     

    Abstract: The layering effect of the coal seam roof poses major influence on the mechanical behavior of the coal-rock system. Herein, the coal seam roof was simplified into coal-rock combinations with different number of bedding planes in the rock unit, and on this basis, uniaxial compression tests were conducted. Then, the stress-strain characteristics, the evolution law of surface strain field and the acoustic emission characteristics during the test were collected and analyzed using the stress monitoring system, the digital image correlation (DIC) method, and the acoustic emission (AE) system. The test shows that: the stress-strain process of the coal-rock combinations can be divided into 4 stages: the fracture compaction stage, linearly increasing stage, unstable failure stage, and post-peak stage. Besides, progressive failures were found to first occur in the coal units, including coal ejection, coal-rock combinations peeling, ejection of peeled coals, and toppling failure. Based on the acoustic emission characteristics, the coal-rock combinations showed a more obvious phenomenon of compaction, small step, and post-peak stress fluctuation during the uniaxial compression process, due to the internal cooperative deformation failure caused by an increasing heterogeneity degree of the combinations. Meanwhile, obvious stress concentration occurs at the “coal-rock” interface in the combination. This is because the physical-mechanical properties of material therein vary greatly, and lateral restraint will be resulted from the adhesive in the bedding surface. Thus, the uniaxial compression of rock unit is changed to the triaxial tension-compression, while that of the coal unit is changed to the triaxial compression. Hence, the “coal-rock” interface is more prone to failure, where the acoustic emission signal is relatively concentrated, and it is more likely to form strain concentration. Therefore, it could be concluded from the study that the coal-rock combination has the equivalent elastic modulus decreased, the integrity weakened, the carrying capacity reduced, and the uniaxial compression strength in a decreasing trend with the increasing number of bedding surfaces in rock units. Generally, the results could provide some guidance for the prevention and control of dynamic disasters, such as rock burst in roadway.

     

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