An Integrated Determination Method of Optimal Supporting Time Against Tbm Jamming

TBM (Tunnel Boring Machine) jamming and support failure occur frequently with inappropriate support timing, particularly when TBM crosses adverse geology. Given this, an integrated determination method of optimal supporting time against TBM jamming was proposed by considering the critical deformation of TBM jamming and the ultimate stress of support. First, a series of numerical tests were conducted to investigate the deformation characteristics of the surrounding rock, the frictional resistance of the TBM shield and the stress of support. Then, the optimal supporting time against TBM jamming was determined by comprehensively analyzing critical deformation and ultimate stress. Finally, the influence of support parameters and measures on determining optimal supporting time in the fault zone was discussed. The results showed that the proposed method for determining the optimal supporting time could reduce the deformation of surrounding rock and the risk of TBM shield jamming and ensure the support's safety. Further, the range of optimal supporting time decreases continuously with the weakening of support parameters. Specifically, the support measures (bolt + steel arch support, shotcrete + bolt support) cannot simultaneously ensure the safety of the support and TBM. The research results can effectively guide the prevention of jamming and support design in TBM tunnels.