An Assessment on the Mechanical Response of Shield Tunnel Induced by Pit Excavation- A Case Study

In order to guarantee the safety of underlying tunnel in excavation phase, a numerical investigation which aims at evaluate the additional internal forces of existing shield tunnels is conducted. Firstly, the additional stresses acting on existing tunnel induced by excavation project is obtained from Mindlin's solution. Then, existing tunnels are treated as an elastic beam resting on Winkler foundation, the response of tunnel including longitudinal deformation, internal forces, caused by adjacent deep excavation is calculated. By considering the uncertainty of soil parameters, tunnel longitudinal stiffness and excavated depth, Monte Carlo simulation technique was applied to predict the expected risk levels quantitatively. Results of a case study indicate a good agreement between calculation and field observation.