Study on excavation sequences and support optimization for shallow-buried and large-spanned tunnels

Based on the engineering characteristics of Baziling Tunnel located on Shanghai-Chengdu Expressway,ABAQUS code was applied to simulate the whole process of excavation and support of the tunnel.The optimized support scheme suggested canceling intermediate wall based on the numerical results.Furthermore,field monitoring of displacement was done in site during the excavation of the tunnel.The variation of displacements shown by numerical results with similation of excavation and support was in agreement with that of the field measurements,while the numerical data were a little greater.From the test results,it was feasible to design shallow-buried and large-spanned 4-lane tunnel without intermediate wall with optimized sequences of excavation and support.The achievements from the Baziling Tunnel would be applied to other tunnels on the expressway.