基于高压电脉冲破岩损伤模型的破岩过程研究

Study on the rock-breaking process based on a high-voltage electropulse boring damage model

高压电脉冲破岩钻进是目前比较具有潜力和接近工业化的一种新型破岩钻进方式。已有的基于PFC2D的高压电脉冲破岩损伤模型未对破岩试验所用的岩石进行参数标定,无法保证模拟的模型与实际破岩试验的岩石力学性质一致。基于室内单轴压缩和巴西劈裂试验的数据结果对天然岩石进行了参数标定,通过标定所得的微观参数建立了与高压电脉冲破岩试验尺寸一致的几何模型,并对高压电脉冲破岩过程进行了仿真研究。仿真结果表明高压电脉冲破岩过程中,以产生剪切破坏为主,同时伴随着一定数量的拉张破坏。之后,利用高压电脉冲破岩试验系统进行了电脉冲破岩试验,得到了直径60 mm、深度22.5 mm的不规则破碎孔,并通过点云软件将破碎效果可视化,放电破岩试验的结果验证了标定所得参数的有效性。最后,通过标定参数建立的几何模型研究了裂隙对高压电脉冲破岩效果的影响,结果表明裂隙的存在会降低破岩过程中的能量消耗,且破碎过程中的破碎区域有向裂隙方向发展的趋势。

High-voltage electropulse boring(EPB)is a new drilling method with great potential for drilling and industrialization.The existing high-voltage electropulse boring damage model based on PFC2D does not calibrate the parameters of the rock used in the rock-breaking test,so it is impossible to ensure that the simulated model is consistent with the mechanical properties of the rock in the actual rock-breaking test.The parameters of natural rock were calibrated based on the data results of indoor uniaxial compression and Brazilian splitting tests.Based on the calibrated micro parameters,a geometric model consistent with the size of the high-voltage EPB test was established,and the EPB process was simulated.The simulation results indicated that the shear failure mainly occurred in the process of high-voltage EPB,accompanied by a certain amount of tensile failure.Then,the EPB test was carried out with the high-voltage EPB test system,and an irregular broken hole with a diameter of 60 mm and a depth of 22.5 mm was obtained.The breaking effect was visualized by point cloud software.The results of the EPB rock-breaking test verified the effectiveness of the calibrated parameters.Finally,the influence of the fractures on the rock-breaking effect of high-voltage EPB was studied through the geometric model established with the calibrated parameters.The results showed that the existence of fractures would reduce the energy consumption in the rock-breaking process,and the crushing area tended to develop in the direction of fractures.