截齿顺次破岩机制的细观数值模拟及截线间距优化研究

为优化镐型截齿在截割头上的布置以提高掘进机截割效率, 借助PFC^3D颗粒离散元数值模拟软件构建了两把截齿顺次截割岩石的三维模型, 对不同截割深度和截线间距组合工况进行了模拟试验, 分析了镐型截齿顺次破岩机制和最优截线间距与截割深度的比值(s/h)。结果表明, 岩石在截齿作用下的破坏模式以张拉破坏占主导, 并伴随挤压和剪切的综合破坏; 截齿顺次截割时, 两相邻截齿之间存在明显的协同作用, 前刀在岩石内残留的裂纹使得岩石易于截割, 可以提高后刀的截割效率; 在模拟试验范围内, 随着s/h值增加, 比能耗呈先减小再增加的变化规律, 模拟结果表明最优s/h值约为3。该研究可为掘进机截割头排布设计提供参考依据。

Microscomic Numerical Study for Mechanism of Sequential Fragmentation by Concial Picks and Corresponding Cutter Spacing Optimization

In order to optimize pick arrangement and improve cutting efficiency of the roadheader, a three-dimensional model of rock chipping process induced by two concial picks was established using 3D granular flow method PFC^3D. Cutting simulation tests with different cutting depths and cutting spacing were performed. The mechanisms of rock fragmentation under sequential cutting and the optimum ratio of cutting spacing to cutting depth (s/h) were investigated. It is found that the fragmentation induced by cutting was dominated by tensile failure, which was accompanied by squeezing and shearing failure. There was a synergistic effect between two picks in the process of sequential cutting. Some cracks left by the previous pick was easily cut by the following cutting operation, thus increasing the cutting efficiency. In the simulation tests, the specific energy consumption showed a trend of rising after an initial falling with the increase of the s/h value, and the optimal s/h value was around 3. This study may be of reference in the design of pick arrangement of a roadheader.