Hoek-Brown failure criterion for damage analysis of tunnels subjected to blast load

Abstract

In this study, a rock tunnel subjected to blast load is modeled mathematically. For this purpose, a cylindrical shell element is used and the motion equations are derived by energy method and Hamilton's principle. In the inner surface of tunnel, different blast holes are considered and its force in radial direction is coupled by motion equations. The structural damping of the structure is assumed by Kelvin-Voigt model. Hoek-Brown failure criterion is utilized for explosion damage analysis of the tunnel. The motion equations are solved numerically by differential quadrature method (DQM). The effect of different parameters such as depth of tunnel, number and diameter of blast holes, type of stone, geological strength index (GSI) and density of stone, type and mass of explosive material are studied on the damage factor of Hoek-Brown criterion. Numerical results show that with increasing the density of explosive material, number and diameter of blast holes, the thickness of damage is increased in the tunnel. In addition, the depth of damage is decreased with increasing strength, GSI, density of rock and depth of tunnel.