刀具破岩机理的细观数值模拟及刀间距优化研究

通过采用RFPA2D软件对全断面岩石掘进机(TBM)盘形滚刀作用下岩石破碎机理进行数值模拟研究.分别模拟了单刀头、双刀头、三刀头作用下的岩体破碎过程,并对多刀头作用时进行了刀间距优化.模拟结果表明,岩石在单刀头作用下的破碎过程大体可以分为粉末体出现、粉核体形成、侧向裂纹产生与扩展、破碎块体出现4个阶段,并体现为以张拉为主、伴随挤压或剪切破坏等复杂破坏形式.在围压作用下,平行于围压方向的裂纹更容易产生与扩展,更有利于刀头侧向裂纹的贯通.多刀头之间有明显的协同作用效应,破碎比能随着刀间距的增加有一个逐渐增加然后减小的过程.数值模拟结果与试验结果吻合较好,可以为岩石掘进机设计、盘形滚刀布置提供参考.

Numerical Modeling of Rock Fracture Mechanism Under Disc Cutters and Associated Cutter Spacing Optimization

In this paper,a numerical code of RFPA was applied to simulate the rock fracture mechanism under disc cutters of TBM.The fracture processes of rock specimens with confining pressure subjected to a single cutter,double cutters and three cutters were investigated respectively,and the cutter spacing was optimized under the action of multi-cutters.The results show that the whole fracture process under the action of single cutter has four stages: powder formation,crack nucleation,side crack initiation and propagation,and chip formation,and the rock fracture is dominated by tensile stress,accompanied by shear stress and compressive stress,etc.Under the confining pressure,the cracks parallel to confining pressure are easier to initiation and propagation,and more beneficial to the coalescence of side crack.Moreover,obvious synergistic effect is found between the neighboring cutters,and with the increase of cutter spacing,the specific energy consumed to rock fracturing increases in the beginning stages,and will decrease,when the spacing is beyond a critical value.The simulation results agree well with experimental ones,and will be beneficial to TBM design and disc cutter arrangement.