Roof stability analysis of deeply-buried cavities based on nonlinear Baker criterion

The dynamic roof stability analysis of deeply-buried cavities is investigated by using the upper bound limit analysis method adopting a more general nonlinear Baker criterion, in contrast to the Hoek-Brown and Mohr-Coulomb criteria which are mainly applicable to rock and soil, respectively. A curved failure mechanism for roof collapse is proposed in the realm of the Baker criterion. The vertical seismic loading is considered herein. The balance equation for work rate is then established after computing the external and internal rates of work. Based on the variational principle, the upper-bound formulation for roof collapse mechanism is derived with/without considerations of the vertical earthquake effects. Accordingly, the closed-form solutions for the failure surface, collapse height and width are explicitly obtained. At the same time, the ABAQUS modelling is used to verify the robustness and validity of closed-form solutions. The parametric studies are carried out to investigate the change laws of the roof collapse mechanism under different parameters. The results indicate that apart from rock/soil properties, the upward seismic force has a significant effect on the failure region above the cavity roof.