基于离散元法的镶齿冲击与切削破岩效果数值分析研究

Numerical analysis on the rock-breaking effect of impacting and cutting actions of inserted tooth cutters based on the discrete element method

随着深地资源的开发,镶齿滚刀在硬岩破碎竖向钻进中的应用愈加广泛。基于高精度拟合的离散元数值模型研究各因素对破岩效果的影响,获得动荷载波动差异系数和比能耗的变化规律。研究发现镶齿破岩以拉伸破坏裂纹为主,齿端曲率是影响微裂纹数量的最关键因素,微裂纹的方位角分布显示,受拉裂纹的分布较均匀,而剪切裂纹的分布主要集中在45°和135°附近。对于不同破岩模式下,镶齿破岩参数与荷载波动情况及比能耗的相关性差异较大,锥角和齿端曲率的影响存在极值,而侵深和攻角表现出单调的相关性。初始压力条件开始对破岩效率有抑制作用,而在与单轴抗压强度比值达到0.8时,比能耗明显下降。随着初始压力系数的增大,微剪切裂纹方位角分布逐渐均布化,而微拉伸裂纹逐渐向水平方向聚集。

With the development of deep ground resources, the inserted-tooth hob is widely used in vertical drilling for hard-rock fragmentation. Based on a high precision fitting discrete element model, the influences of various factors on rock-breaking efficiency were studied, and the variation of load fluctuation difference coefficient and specific energy consumption were revealed. The results show that the tensile crack is the main failure pattern of the inserted-tooth cutter, and the tooth tip curvature is the most significant factor affecting the number of microcracks. The distribution of azimuth angle of microcracks shows that the distribution of tensile crack is uniform, while the distribution of shear crack is mainly concentrated near 45° and 135° regions. For different rock-breaking modes, the correlation between rock-breaking parameters and load fluctuation or specific energy consumption is different, the influences of cone angle and tooth tip curvature have their extreme value, while the penetration depth and attack angle show monotonous correlation. The initial pressure condition inhibits rock breaking efficiency, but when the ratio of the pressure to uniaxial compressive strength reaches 0.8, the energy consumption decreases significantly. With the increase of the initial pressure coefficient, the azimuth distribution of micro-shear cracks gradually homogenizes, while the micro-tensile cracks gradually converge in the horizontal direction.