软分层对煤的单轴压缩力学特性影响研究

Study on Influence of Soft Coal Interlayer on Mechanical Properties of Coal Under Uniaxial Compression

为了探究松软构造煤分层对原生煤样单轴压缩力学参数和破坏模式的影响程度和影响规律,在室内试验得出的宏观力学参数的基础上,采用PFC2D软件对含有不同厚度和倾角构造软煤分层的原生煤样试样进行数值模拟,分析试样受荷后的细观力学响应机制;根据试验结果,建立松软构造煤分层与荷载耦合作用下煤的单轴压缩损伤模型,探讨构造煤赋存参数对试样破坏形态演化的影响。研究结果表明:构造软煤分层厚度是影响复合煤层试样单轴抗压强度的重要参数,当软煤分层厚度增加时,导致含软煤分层的试样单轴抗压强度降低;软煤分层的倾角主要影响试件内部裂纹的萌生和扩展方式,倾角越大,剪切裂纹萌生的时间越晚,剪切裂纹在总裂纹数中所占比例越小;含软煤分层的试样破坏主要包括沿交界面的层裂破坏、拉伸破坏和复合破坏3种类型,破坏类型主要与含软煤分层的倾角相关。

In order to explore the influence degree and law of soft structure coal interlayer on the uniaxial compression mechanical parameters and failure mode of primary coal samples, based on the macro-scopic mechanical parameters obtained from the indoor test, the standard coal samples with different thickness and dip structure soft coal interlayer are simulated by PFC2D software, and the micro mechanical response mechanism of the samples under load is analyzed. According to the test results, the uniaxial compression damage model of coal under the coupling action of soft structure coal interlayer and load is established, and the influence of structural coal occurrence parameters on the failure mode evolution of the sample is discussed. The results show that:the thickness of soft coal interlayer is an important parameter affecting the uniaxial compressive strength of composite coal seam samples. When the thickness of soft coal interlayer increases, the uniaxial compressive strength of samples in soft coal interlayer decreases. The dip angle of soft coal interlayer mainly affects the initiation and propagation mode of internal cracks. The larger the dip angle, the later the initiation time of shear cracks, and the smaller the proportion of shear cracks in the total number of cracks. There are three types of failure of soft coal intercalation: spallation failure along the interface, tensile failure and composite failure. The failure type is mainly related to the dip angle of soft coal intercalation.