循环冷加载条件下受载煤样结构损伤规律

发布时间：2018-03-24 18:51

  本文选题：循环冷加载　切入点：裂隙结构　出处：《煤炭学报》2017年09期

【摘要】：煤体是具有孔隙、裂隙结构的固体介质,孔隙的贯通程度、裂隙的宽度是煤层渗透能力的重要指标,为了使煤体裂隙结构发生损伤而达到增透的目的,对三轴受载煤样进行注液氮冷加载实验,利用液氮注入钻孔煤实验装置系统对煤样施加4 MPa围压,分别进行多周期冷加载作用,通过高倍相机、金相显微镜、声波测速仪和CT成像系统观测煤样表面裂隙宽度、波速衰减率及内部结构损伤情况。根据单轴压缩实验的应力-应变曲线,分析煤样结构随冷加载周期的变化规律。结果表明:(1)煤样裂隙结构损伤程度随冷加载周期的增加而增大,损伤速率随注液氮周期的增加呈现先增加后降低的非线性变化规律;(2)煤样经6周期注液氮冷加载后表面发生颗粒脱落,经过7周期注液氮冷加载后发生宏观碎裂;(3)冷加载对煤样原生裂隙损伤效果显著,并沿着层理方向延伸。液氮冷加载能使煤体结构发生显著损伤,这为冲击地压灾害防治与瓦斯治理提供了新的方法。
[Abstract]:Coal is a solid medium pore, fracture pore structure, through the degree, the width of the fracture is an important index of coal seam permeability, in order to make the coal fracture structure damage and achieve the purpose of increasing permeability, loading coal injection liquid nitrogen cold loading experiment of three axes, using liquid nitrogen drilling coal injection system the experimental device applied 4 MPa confining pressure of coal samples, respectively. Effect of multi cycle cooling load, through high magnification camera, microscope, width of acoustic velocity meter and CT imaging observation system of coal surface crack, wave attenuation rate and internal structure damage situation. According to the stress-strain curve under uniaxial compression experiment, analysis the structure of coal changes with cold loading cycles. The results showed that: (1) the degree of structural damage fracture of coal samples increases with cold loading cycles, the damage rate is nonlinear first increase and then decrease with the increase of liquid nitrogen cycle Changes in the law; (2) coal samples after 6 cycle injection liquid nitrogen cooled after loading the surface particles, after 7 cycles of loading after injection of liquid nitrogen cooled macro fragmentation; (3) the cold load significantly on the coal crack damage effect, and extends along the direction of loading. Liquid nitrogen cold can make the coal structure significantly damage and this provides a new method for prevention of shock and gas pressure disaster management.

【作者单位】： 辽宁工程技术大学力学与工程学院;河北科技大学建筑工程学院;
【基金】：国家自然科学基金资助项目(51704142,51474121,51574139)
【分类号】：TD324.1;TD712
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本文编号：1659579