In conventional studies, the blasting seismic wave is always treated as a time-harmonic wave, which is not suitable in some situations due to its short duration. In this paper, the blasting P-wave is simplified as a triangular impulse. The distribution functions of dynamic stress concentration factor (DSCF) and the radial and hoop vibration velocity scaling factors (RVSF and HVSF) around the circular tunnel are derived based on the Fourier–Bessel expansion method. Then, the effects of the rising duration, the total duration and Poisson's ratio on DSCF, RVSF and HVSF are discussed. Results show that (1) the maximum RVSF and HVSF are located at the incident side, and the location of the maximum DSCF will move from the incident side to the shadow side when the total duration increases; (2) the maximum DSCF increases with the increasing total duration, decreases with the increasing Poisson's ratio, but is immune to the ratio of the rising to total duration; (3) the maximum RVSF decreases with the increase of the total duration and the ratio of the rising to total duration, but increases with the increasing Poisson's ratio; (4) the maximum HVSF decreases with the increase of the total duration and the ratio of the rising to total duration, but is immune to Poisson's ratio; (5) the RVSF and HVSF under triangular impulses gradually change from less than those under time-harmonic waves to greater than those under time-harmonic waves with the increasing total duration, but the DSCF shows the opposite trend.

Shale is composed of a rock matrix and bedding planes with a layered structure, resulting in significant anisotropy in its mechanical properties. In order to study the anisotropic mechanical properties of shale, the shale samples were prepared in different orientations with respect to the bedding planes, and the composition and microstructure of shale were first analyzed by X-ray diffractometer (XRD) and scanning electron microscope (SEM), and then the uniaxial and triaxial compression experiment on shale samples with five different bedding angles (the angle between the loading direction and the normal direction of the bedding planes, 0°, 30°, 45°, 60°, and 90°) were conducted under five confining pressures (0, 10, 20, 30, and 40 MPa), respectively; meanwhile, the acoustic emission (AE) test was carried out in the uniaxial test. The results indicate that the mechanical properties and parameters of shale have obvious anisotropy, and the AE characteristics of shale samples with different bedding angles are significantly different during uniaxial loading. Furthermore, the compressive strength and elastic modulus of the shale samples first decrease and then increase with the increase in the bedding angle under different confining pressures. Moreover, according to the anisotropic grade of compressive strength, the shale has moderate anisotropy. In addition, the failure mode of the shale samples is also anisotropic, and varies with the bedding angle and confining pressure.

The stress waves generated by tunnel blasting in urban rock layers can affect the safety of adjacent buried structures in the overlying geological layers. To ensure the safety of buried structures, it is crucial to understand the blasting vibration characteristics in the geological layers. In this paper, the analytical solution for the vibration velocity response in geological layer subjected to P-wave is derived. Based on a specific tunnel blasting excavation project, the influence of incident wave frequency, layer thickness, and incidence angle on the vibration velocity distribution along the depth direction are investigated. Results show that the vibration velocity in the upper soil layer does not strictly attenuate with increasing distance from the blasting source but rather exhibits a fluctuating trend. As the frequency of the incident wave increases, the normalized vibration velocity on the ground surface exhibits a periodic decreasing trend, and the distance between the initial fluctuation point and the ground surface decreases. The normalized vibration velocity in the soil layer does not exhibit a monotonic decrease as the soil thickness increases. With an increase in the incident angle, a general declining pattern is observed in the normalized vibration velocity along the depth direction.

Blast-induced vibrations from newly constructed tunnels may adversely affect adjacent existing tunnel structures. To ensure the safety of the existing tunnel, it is essential to investigate its dynamic response under blast disturbances. Based on an expansion project for a highway double-arch tunnel, this study employed the dynamic finite element program LS-DYNA to analyze the vibration velocity and effective stress in the tunnel lining subjected to blast vibrations. The distribution characteristics of vibration velocity and effective stress at different locations of tunnel lining were obtained. A relationship model between the peak particle velocity (PPV) and effective stress was established. According to the maximum tensile stress theory, a safety criterion based on vibration velocity was determined. To facilitate field monitoring, a correlation between the vibration velocity at the arch waist and foot was established, leading to a proposed safety threshold for the arch foot vibration velocity. Furthermore, a statistical relationship was developed between the charge weight per hole in the upper bench cut and the vibration velocity at the arch foot to guide blasting design. Using the arch foot vibration velocity as the safety standard, the maximum permissible charge weight to ensure the structural safety of the existing tunnel was recommended.