Effect of Underground Stress Waves with Varied Wavelengths on Dynamic Responses of Tunnels

Underground dynamic loads are usually caused by underground railways, drilling, blasting and so on. Compared with the dynamic loads on the ground, in the condition of underground dynamic loads, there are some differences in the propagation characteristics of stress waves and the effect on dynamic responses of underground structures. In this paper, the underground dynamic loads expressed as harmonic waves were assumed to be applied at some distance from the top of a tunnel. Based on the finite difference software FLAC^3D, the harmonic waves of varied wavelength–diameter ratios were considered in the analysis, in order to obtain the regularities of dynamic responses of the tunnel. Accelerations, velocities, maximum principle stresses and minimum principle stresses for the tunnel under different wavelength–diameter ratios were calculated in the numerical simulations. The variations of the peak accelerations, peak velocities, peak maximum principle stresses and peak minimum principle stresses with wavelength–diameter ratios were obtained. The calculation results can help provide a reference for dynamic protection of underground structures.