Computational Modeling of Underground Tunnels in Intact and Jointed Rock

摘要

Computational models were developed to predict the dynamic response and damage toreinforced tunnels in rock subjected to ground shock from nuclear weapons. This effort is part of the Underground Technology Program. The finite element calculations were performed with the DYNA3D code using a comprehensive smooth-cap model for intact rock and a nonlinear slideline model for rock joints. Calculated tunnel closures, and free-field stress and velocity histories, compare well with spherical wave tests (SWAT) on aluminum lined tunnels in intact limestone. The intact rock model includes a scalar anisotropic damage formulation for modeling strain-softening and modulus reduction, viscoplastic formulations and rate-shifted damage surfaces for modeling rate effects, and a three-invariant plasticity formulation. Preliminary stack of bricks calculations were also performed to verify our joint model, in preparation for future predictions of tunnel response in jointed limestone.