复合岩体的TBM破岩机理数值模拟

Mechanism of rock fragmentation analysis by TBM cutters in mixed-face conditions

为了指导TBM刀盘刀具的研制和不同地质条件下刀盘刀具的选型,TBM破岩机理的研究成为核心。在TBM滚刀的作用下,岩体中裂纹的生成、扩展和连接规律是深刻理解TBM破岩机理的前提,因此,TBM滚刀破岩机理的研究具有重要的工程应用价值。目前,TBM滚刀破岩机理的研究主要集中在单一岩体中,但在TBM施工过程中会遇到各种复杂的地质条件。笔者采用离散元方法,研究了复合岩体的破岩机理,复合岩体中岩片的形成不同于单一岩体,其裂纹的最终连接是由起裂于复合岩体交界面上的微裂纹的扩展,将两滚刀之间的赫兹裂纹连接,最终形成岩片。因此,在一定情况下复合岩体更有利于TBM隧道施工。

The study of rock fragmentation mechanism by TBM cutters is the key to guide the development of TBM cutterhead and the selection of cutterhead in different geological conditions.The formation,propagation and coalescence of cracks in rock masse is the precondition of understanding the rock fragmentation mechanism by TBM cutters.Therefore,the study of rock fragmentation mechanism by TBM cutters is significant for engineering application.At present,the study of rock fragmentation mechanism mainly concentrates on the single rock. However,the complicated geological conditions are oftenencountered during the excavation of tunnels by TBM.In this paper,a discrete element method is employed to study the fragmentation mechanism of the composite rock mass.It could be obtained from the numerical results that the propagation of microcracks initiated from the interface leads to the coalescence of Hertzian cracks between two cutters,and the formation of chipping.Therefore,under certain conditions,the formation of chipping in composite rock mass by TBM becomes easier than that in the single rock.