School of Safety Science and Engineering, Anhui University of Science & Technology
Institute of Energy, Hefei Comprehensive National Science Center

为研究地应力影响下聚能爆破对煤层的损伤情况及裂纹扩展规律,以聚能爆破作用机理和地应力下爆破孔环向应力分布规律为理论基础,通过相似模拟试验和数值模拟与分形维数相结合的方法,探讨了地应力作用下聚能爆破煤体裂纹扩展规律。试验结果表明:相对于无地应力条件,3组对照试验1#测点的应力大小和动载作用时间均减少,证明地应力对聚能爆破存在抑制作用。聚能爆破受地应力的影响会减少裂纹发育的长度,但依然能够保证裂纹的定向发育。当聚能方向平行于最大主应力方向时,聚能方向裂纹会得到延长;反之,裂纹长度将会减少。通过ANSYS/LS-DYNA对不同侧压系数(k)下煤体聚能爆破进行模拟,结果表明:k越大对聚能方向裂纹发育抑制越明显;k越小则对聚能方向裂纹发育起促进作用。同时,通过线性拟合得到损伤量w和分形维数D之间的函数关系,建立了煤体损伤预测模型。

This study is aimed at revealing the damage characteristics and crack propagation law of coal during concentrated shaped charge blasting under the influence of in-situ stress. First, based on the mechanism of concentrated shaped charge blasting and the circumferential stress distribution law of blast hole under in-situ stress, the crack propagation law of coal during concentrated shaped charge blasting under in-situ stress was investigated by combining similar simulation experiments and numerical simula- tions with the fractal dimension method. According to the experimental results, compared to the case without in-situ stress, the stress magnitude and dynamic loading time at the 1 # monitoring point decrease in all the three groups of control experiments, indicating that in-situ stress has an inhibitory effect on concentrated shaped charge blasting. The influence of in-situ stress on concentrated shaped charge blasting reduces the length of generated cracks, but concentrated shaped charge blasting still manages to ensure the oriented crack growth. When the direction of concentrated shaped charge is parallel to that ofthe maximum principal stress, cracks in the direction of concentrated shaped charge will be extended; otherwise, the crack length will be shortened. The concentrated shaped charge blasting simulation on coal under different lateral pressure coefficients (k) using ANSYS/ LS-DYNA reveals that a larger k value leads to a more significant inhibitory effect on crack propagation in the direction of concentrated shaped charge, while a smaller k value promotes such crack propagation in turn. In addition, a function relationship between the damage amount w and the fractal dimension D was obtained through linear fit- ting, and a prediction model for coal damage was established.

国家自然科学基金项目(52074013);安徽省教育厅高校自然科学基金项目(YJS20210395,YJS20210396);安徽理工大学2023年研究生创新基金项目(2023CX1004)