Simulation of the inclined jointed rock mass behaviors in a mountain tunnel excavation using DDA

Assessing the stability of a mountain tunnel in complex geological conditions during construction is a challenging task. Although the Discontinuous Deformation Analysis (DDA) method has been applied in many rock engineering problems, its accuracy as a tool for analysis of tunnel excavation in a complex geological condition (e.g., involving sloping ground and jointed rock mass) needs further validation. In this paper, the DDA simulations of a tunnel excavation under various conditions (e.g., different dip angles and locations of the tunnel in the slope) were verified with physical tests (e.g., "trap-door" tests) in two main aspects, the sloping ground subsidence and the stress distribution of the jointed rock mass induced in the excavation. The results showed that the DDA was able to simulate, accurately, the mechanical behaviors of the inclined jointed rock strata in a tunnel excavation. The applicability of the DDA in such tunnel excavation projects is implicated.