The crushing and deformation behavior of gangue aggregate is a key factor affecting the stability of the overburden in goaf, and the particle size gradation has a significant impact on the particle fragmentation and compressive deformation of gangue aggregate. In this study, compression tests on crushed gangue aggregates with different particle size gradations were conducted, and the fragmentation of gangue was quantitatively characterized by using fractal dimension. Additionally, a lateral confined compression particle flow model for gangue was established, the meso-structural evolution law of gangue aggregates under triaxial compression under different gradation conditions was studied, and the influence mechanism of the internal microstructure of crushed gangue on its macroscopic deformation was revealed. The research results indicate that: (1) the larger the Talbot coefficient n, the higher the gangue fragmentation rate and the larger the sample deformation. The deformation of the gangue sample primarily results from the compaction of voids and the fragmentation of the block. Void deformation mainly occurs in the early loading stage, and deformation amount of the gangue sample caused by void compaction accounts for about 60 %. The fragmentation deformation runs through the entire loading process, and the deformation amount of the gangue sample caused by block fragmentation accounts for about 40 %. (2) There is a good linear regression relationship between the fractal dimension n and the fragmentation rate, and the larger the initial gradation, the smaller the fractal dimension. During the loading process of the sample, large particle size gangue is mainly subject to fragmentation, while small particle size gangue mainly fills the gaps. Moreover, small particle size gangue can effectively weaken the stress concentration effect. (3) As the axial stress increases, the failure mode changes from tensile failure to shear failure, and the block contact mode gradually changes from point contact to surface contact. The stress-bearing zone extends from the top to the entire specimen, and the contact force chain between the gangue changes from circular to cylindrical shape, and the force chain gradually becomes directional. (4) The energy generation mainly comes from the friction and fragmentation between gangue blocks, and the strain energy generated by fragmentation is dominant. The variation of total energy can be divided into three stages: gradual increase stage, sharp increase stage, and stable stage.

中文翻译：

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荷载作用下颗粒破碎对不同级配煤矸石骨料压缩变形的细观影响机制


煤矸石骨料破碎变形行为是影响采空区覆岩稳定性的关键因素，而粒度级配对煤矸石骨料颗粒破碎和压缩变形影响显着。本研究对不同粒度级配的破碎煤矸石骨料进行了压缩试验，利用分形维数定量表征了煤矸石的破碎情况。此外，建立了煤矸石横向约束压缩颗粒流模型，研究了不同级配条件下煤矸石骨料在三轴压缩下的细观结构演化规律，揭示了破碎后煤矸石内部微观结构对其宏观变形的影响机制。 。研究结果表明：（1）Talbot系数n越大，煤矸石破碎率越高，样品变形越大。煤矸石样品的变形主要是由于空隙的压实和块体的破碎造成的。空洞变形主要发生在加载初期，由空洞压实引起的煤矸石样品变形量约占60%。破碎变形贯穿整个加载过程，块状破碎引起的煤矸石样品变形量约占40%。 (2)分形维数n与破碎率之间存在良好的线性回归关系，且初始级配越大，分形维数越小。样品加载过程中，大粒径煤矸石主要发生破碎，小粒径煤矸石主要填充空隙。 而且，小粒径煤矸石可以有效减弱应力集中效应。 (3)随着轴向应力的增大，破坏模式由拉拉破坏转变为剪切破坏，块体接触模式逐渐由点接触转变为面接触。受力区从顶部延伸至整个试件，煤矸石之间的接触力链由圆形变为圆柱形，且力链逐渐变得有方向性。 (4) 能量的产生主要来自于煤矸石块之间的摩擦和破碎，其中破碎产生的应变能占主导地位。总能量的变化可分为三个阶段：逐渐增加阶段、急剧增加阶段和稳定阶段。