Two Neighbouring Tunnels in Saturated Soil Under Blast Loading

The paper deals with the numerical modelling of the blast-induced deformation of two neighbouring shallow tunnels and the surrounding soil. The deformation is caused by an explosion inside one of the tunnels. The explosion is simulated by a short-term pressure load of moderate amplitude (8 MPa) applied to the tunnel lining. The lining of both tunnels is circular with an inner diameter of 9.6 m and consists of concrete segments (tubbings) assumed to be linearly elastic. The tunnels are located at a depth of 17 m in fully saturated soil. The effective stresses in the soil are described by a hypoplasticity model. The modelling incorporates pore water cavitation at zero absolute pore pressure. The dynamic problem is solved in a two-dimensional plane-strain formulation with the finite-element program Abaqus/Standard. The transient deformation of the tunnel lining and the soil is analysed in detail. In particular, the solution reveals the emergence of large cavitation zones in the soil during the dynamic deformation.