Numerical Simulation of Zonal Disintegration of the Surrounding Rock Masses Around a Deep Circular Tunnel Under Dynamic Unloading

A new numerical method, which is called the General Particle Dynamics (GPD) method, is proposed to investigate the zonal disintegration mechanism of isotropic rock masses around a deep circular tunnel subjected to dynamic unloading as well as the stress distributions. A constitutive model based on the GPD method is developed to simulate the zonal disintegration phenomenon in deep rock masses. The number and size of fractured and nonfractured zones are determined using the nonlinear unified strength criterion. It is shown from the numerical results that the dynamic loads and high in situ stress are two dominant factors for the occurrence of zonal disintegration.