超临界CO2气爆非均质煤体破裂规律模拟研究

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M atlab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,初应力对主裂缝的萌生和扩展具有导向作用,气爆裂缝沿最大初应力方向扩展;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.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.

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

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 that the initial stress has a guiding effect on the generation and propagation of the main cracks,and the cracks propagate along the direction of the maximum initial stress.For a given dip angle of the weak plane,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,and 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.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.