Effects of Rock Joints on Failure of Tunnels Subject to Blast Loading

Abstract : This project provided the basis for numerical simulations of tunnel failure under blast loads. The challenges included handling large deformations, complex failure modes, multiple failure planes and rock joints with various orientations. Meeting these challenges depended critically on developing appropriate constitutive equations for rock, and a robust, efficient numerical procedure for studying failure induced by waves in the host rock interacting with a tunnel. This research formulated constitutive equations that combined continuum and discontinuum aspects of material response in order to capture essential physical features of rock, such as joints and faults with variable strength and orientation, multiple failure orientations, and a spectrum of failure modes that includes axial splitting and various combinations of shear and opening modes. The numerical approach was based on the material-point method (MPM) that handles large continuum deformations. A constitutive model that predicts fractures was combined with MPM to study rock failure in the vicinity of a tunnel. Moreover, a one-dimensional study of the effect of joints on a propagating wave pulse was performed showing the net transmission through a joint set.

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