Analysis on Deformation and Failure Mode Characteristics of Surrounding Rock of Multi-arch Tunnel by DDA Method

Abstract:

The surrounding rock of multi-arch tunnel is intermittence jointed rock masses in most cases; it’s more realistic to analyze the deformation and failure mode characteristics of this kind of rock with discontinuous deformation analysis (DDA) method. The deformation and failure process of surrounding rock of Jinjishan multi-arch tunnel was simulated and the whole failure process was divided into 3 stages: rock deformation, surface subsidence and slip plane appearing above the mid-partition; slip planes (or bands) forming on both sides of tunnel; the rock mass instability above the mid-partition and rapid collapsing of rock mass above the tunnel. The paper studied the deformation and failure characters of shallow and deep surrounding rock in Jinjishan tunnel with the conclusion that the sidewall of the tunnel, the dome or the inside spandrel close to mid-partition and the outside spandrel would be first deformed.