Assessment of underground tunnel stability to adjacent tunnel explosion: Fid-Bau Portal

Assessment of underground tunnel stability to adjacent tunnel explosion

Li, J.C. / Li, H.B. / Ma, G.W. / Zhou, Y.X.

Highlights ► We present a method to predict underground tunnel behavior. ► Tunnel vibration is sensitive to the loading density in the charge tunnel. ► More severe vibrations can be observed for greater loading density. ► The maximum radial stress occurs in the tunnel wall nearest to the charge. ► The maximum radial stress decreases with increasing distance to the tunnel.

Abstract A theoretical method to predict underground tunnel behavior considering the peak particle velocity (PPV) and the stress distribution is presented in this study. The influence of explosion-induced wave from an underground charge tunnel on an adjacent tunnel is explicitly considered in order to evaluate tunnel stability. According to the wave propagation law in rock and the conservation of the momentum on the wave front, the motion equation of the adjacent tunnel wall is first derived in the paper. A case study is carried out and the analytical method is calibrated by comparing the PPV of the adjacent tunnel wall with empirical formulae results. The tunnel safety is then assessed by analyzing the PPV and the stress distribution. Parametric studies regarding the effects of the separation distance and the loading density on the potential brittle failure of the adjacent tunnel wall are also conducted. The safe separation distance between the two adjacent tunnels is predicted and compared with those from the empirical PPV criterion and the maximum tensile strength criterion.