Back Analysis and Real-time Construction Application of Tunnel Surrounding Rock Parameters

Based on the displacement deformation monitoring data of a certain tunnel surrounding rock,the surrounding rock elastic modulus Eand the initial stress of lateral pressure coefficient K were selected as inversion parameters.And then the displacement back analysis optimization calculation were implemented on the shallow buried portal and central of tunnel surrounding rock with the golden section method and FLAC3 Dnumerical simulation.The rock mechanical parameters obtained by back analysis were applied to the numerical simulation of deformation of the surrounding rock which located in front of the tunnel face.The results were compared to the real-time monitoring results in tunnel construction.The feasibility of displacement back analysis in the real-time construction was verified.Meanwhile,the predicted results of vault settlement was used to set rock excavation deformation allowance.The quantity of shotcrete was reduced by controlling the over break volume,and the project cost was also saved.