energy evolution and blast response of segmented circular tunnels; considering depth and different soils

energy assessment of deep tunnels depends on the depth and what kind of ground they surrounded by. the numerical results showed that high static compressive stress concentration around the underground tunnel results in the accumulation of substantial strain energy at the same location. the roof and floor of the tunnel are more prone to dynamic failures during the blasting loading process. in addition, the analysis of energy dissipation indicated that the strain energy reduction and the residual kinetic energy are positively related to the lateral pressure coefficient and the burial depth of the tunnel, and the residual kinetic energy is much larger than the strain energy reduction under the same condition. furthermore, for an underground tunnel subjected to high in situ stress, the blasting stress wave with lower amplitude is sufficient to trigger severe dynamic failures. results indicate that a tunnel in saturated soil is more vulnerable to severe damage than that buried in either partially saturated soil or dry soil. the tunnel is also more vulnerable to surface explosions that occur directly above the centre of the tunnel than those that occur at any equivalent distance in the ground away from the tunnel centre.