Abstract：A new mechanical model is proposed to investigate the zonal disintegration mechanism of isotropic rock masses around a deep circular tunnel subjected to dynamic unloading under hydrostatic pressure condition as well as the total elastic stress-field distributions. Effects of unloading rate and dynamic mechanical parameters of isotropic deep rock masses on the zonal disintegration phenomenon of the surrounding rock masses around a deep circular tunnel are taken into account.The number and size of fractured and non-fractured zones is determined using the Hoek-Brown criterion. Numerical computation is carried out. It is found from numerical results that the number and size of fractured and non-fractured zones significantly depend on unloading rate and dynamic mechanical parameters of deep rock masses.
2013, Vol. 34 
