Elastic-slip interface effect on dynamic stress around twin tunnels in soil medium subjected to blast waves

Abstract

Blasting excavation of deep-buried structures is a complex dynamic process which can cause blast loading and insitu stress redistribution. An elastic-slip interface model is introduced to analyze the dynamic response of twin tunnels subjected to blast waves. The blast waves is expressed by Fourier-Bessel expansion method of wave function, and the wave field is superimposed by Graf coordinate transformation method. To analyze the interface effect, the elastic and slip coefficients of interface are introduced to describe the interface properties. Through numerical examples, it is found that the dynamic stress at the upper points of tunnels is larger than that at the sides of tunnels. However, the interface effect on the dynamic stress at the sides of tunnels is larger than that at the upper points, especially a small distance between twin tunnels is selected. Due to the interface effect, not only compressive but also tensile deformations can be seen, and the large oscillation of dynamic stress at the sides of tunnels can be observed. Excellent agreement with existing numerical results validates this dynamic model.