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Simulation of fracturing low of heterogeneous coal caused by supercritical CO2 explosion

DOI：

 作者 单位 邮编 陈鹏 力学与工程学院 123000 孙可明 理学院 266000

为揭示超临界CO2气爆含割理裂隙非均质煤体的致裂规律，开发了识别实际煤体图像获取其割理裂隙几何信息的Matlab程序，将几何信息与煤体非均质物性参数关联并导入Abaqus中，实现了非均质煤体有限元表征，并采用SPH与FEM联合求解的方法模拟超临界CO2气爆非均质煤体的致裂过程，得到了弱面倾角、弱面到爆孔中心距离及初应力的变化对煤体气爆致裂效果的影响规律。模拟结果表明：弱面对应力波有吸收和反射作用，对气爆裂缝扩展有阻碍作用；弱面倾角相同时，弱面离爆孔越近，穿过弱面的裂缝尺度和密度越大，弱面离爆孔较远时，弱面完全阻断了裂缝的扩展；弱面到爆孔中心距离相同时，弱面倾角越大，弱面对裂缝扩展的阻碍作用越大，穿过弱面的裂缝尺度和密度越小，应力波透射率越小，应力波透射率衰减度越大；初应力对主裂缝的产生和扩展具有导向作用，气爆裂缝沿最大初应力方向扩展；现场气爆增透煤体时应考虑割理裂隙和地应力特征合理布置气爆孔位置及爆破参数。

In order to reveal the fracturing law of heterogeneous coal with cleats caused by supercritical CO2 explosion. A Matlab code was developed to identify the actual coal image and obtain the geometric information of its cleats. The geometric information was related to the heterogeneous physical parameters of coal and imported into Abaqus to realize the finite element representation of heterogeneous coal. SPH and FEM were used to simulate the fracture process of heterogeneous coal caused by supercritical CO2 explosion.The dip angle of the weak plane, the distance from the weak plane to the center of the blast hole and the initial stress on the fracturing effect of the coal gas explosion was obtained. The simulation results indicated the weak plane can absorb and reflect the stress wave and hinder the propagation of gas explosion cracks. For a given weak plane dip angle, the weak plane is closer to the blast hole, the size and density of the cracks passing through the weak plane is greater; when the weak plane is farther from the blast hole, the weak plane completely blocks the cracks propagation. For a given distance from the weak plane to the center of the blast hole, the greater the dip angle of the weak plane, the greater the blocking effect of the weak plane on cracks propagation, the smaller the size and density of the cracks passing through the weak plane, the smaller the stress wave transmittance, the greater the attenuation of stress wave transmittance. The initial stress has a guiding effect on the generation and propagation of the main cracks, and the gas explosion cracks expand along the direction of the maximum initial stress. When gas explosion on site increases the permeability of coal, the location of gas explosion hole and blasting parameters should be rationally arranged in consideration of the cleats and in-situ stress characteristics.
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