Abstract: For soft rock that having rheological properties, like the carbonaceous schist, the modified Burgers model, which is the combination of Burgers model and Mohr-Coulomb model, can characterize its visco-elastic-plastic deformation behavior. In a tunnel excavation project, the squeezed deformation zone with soft rock mass was numerical analyzed and the rheological model parameters are calibrated throughout the back analysis. The paper discusses the interactions between the carbonaceous schist rock mass and the supporting structures. The optimization of the time for the tunnel excavation supporting is made possible by using the numerical analysis results, regression analysis results and the construction monitoring data.

Key words: Carbonaceous Schist, Tunnel Excavation, Rheological Properties, Interactions, Time to Support