简单复合岩体中TBM多滚刀破岩机理离散元分析

Distinct element analysis of mechanism of rock fragmentation induced by TBM cutting in simply composite rock mass with multiple cutters

采用引入考虑胶结尺寸的微观接触模型的PFC2D离散元软件,对全断面岩石掘进机(TBM)盘形滚刀作用下简单形式的复合岩体破岩机理进行数值模拟研究。进行了单滚刀、双滚刀和三滚刀作用下的复合岩体破碎过程的模拟。模拟结果表明:滚刀破岩过程可以分为三个阶段:加载阶段、卸载阶段和残余跃进阶段。通过双滚刀和三滚刀侵入复合岩体的推力-侵深曲线分析,软岩上的滚刀比硬岩上的滚刀进入各阶段稍慢,略有滞后;不同滚刀间的峰值法向推力相差较大,易造成滚刀磨损。对于花岗岩-绿片岩复合岩体,破岩时接触力链被岩体分界面分割,硬岩区胶结破坏数目较多,双滚刀、三滚刀侵入时易形成贯通裂缝;破岩效率由大到小为双滚刀效率、三滚刀效率、单滚刀效率,而且双滚刀能够将效率提高一倍左右。

The PFC2D software,incorporated with a size-dependent bond contact model,was employed to investigate the fracture mechanism induced by TBM cutting in simply composite rock mass.The rock fracture process was simulated under the action of cutting with single,double and triple cutters.The numerical results show that the process of rock fragmentation can be described with three stages:loading stage,unloading stage and residual leap stage.The analysis on the thrust-intrusion depth curve for the cutting in composite rock mass with double and triple cutters demonstrates that the cutter reaches the three stages is slightly slower on soft rock than on hard rock.A large difference was observed between/among cutters on the peak normal thrust,which will induce the wear of the cutters easily.For the rock mass composited by granite and greenschist,contact force chains are segmented by the interface between hard rock and soft rock,and bond breakage of hard rock is more than of soft rock,and through cracks form easily in double and triple cutters breaking rock.Rock breaking efficiency by double cutter is larger than by triple cutter with the latter larger than by single cutter.Besides the breaking efficiency by the double cutter is almost twice as that in other cases.