TBM隧道围岩-支护动态相互作用机制研究OA北大核心

Compared with the mining method,the TBM method has the characteristics of lagging construction and time-sensitive performance.The existing theoretical results are difficult to accurately describe the dynamic interaction process between the surrounding rock and support of the TBM tunnel.Based on the characteristics of the interaction between surrounding rock and the development characteristic of the support structure stiffness in TBM tunnels,a virtual support force was introduced to simulate the spatial support effect of the excavation face.A mechanical model of the interaction between surrounding rock and support was established,which comprehensively considered the timing and time characteristics of TBM tunnel support structure construction.The theoretical model was verified through numerical simulation and on-site testing.The influence of factors such as excavation speed,bolt mortar hardening speed,shotcrete timing,and shotcrete hardening speed on the displacement around the tunnel and the primary support structure support force were analyzed.The corresponding support suggestions were provided.The research results indicate that the dynamic interaction model between TBM tunnel surrounding rock and support can provide analytical solutions for the displacement around the tunnel at any time and cross-section,as well as the support forces of bolts,steel arches,and shotcrete.After the application of the bolts and steel arches,the deformation rate of the surrounding rock significantly decreases.Before the application of shotcrete,the deformation of the surrounding rock has stabilized.The main function of shotcrete is to prevent falling blocks and serve as a safety reserve.The increase of hardening speed of mortar can enhance the support force of bolt.Timely application of shotcrete can significantly improve the primary support structure support force and improve the stress state of bolt and steel arch.Accelerating the hardening speed of shotcrete can improve the overall support effect and reduce the surrounding rock pressure borne by steel arch and bolt.Under normal construction conditions,the primary support performance can be improved by reducing the TBM excavation speed and selecting fast hardening bolt mortar.When crossing sections with broken rocks and poor stability,the shotcrete should be operated at a distance of no more than 3 times the tunnel diameter from the excavation face.The shotcrete materials with fast hardening speed should be selected to further improve the bearing capacity of the support system.The research results can provide a theoretical basis for further optimizing the design and construction of the support in TBM tunnels.