Surface Vibration Cavity Effect of Underpass Blasting in Urban Metro Liaison Channel

The study of surface vibration attenuation law of urban underground engineering blasting construction is of great significance for the protection of adjacent buildings. This paper takes the Wuhan Metro Line 8 Phase Ⅱ liaison channel blasting excavation project as an example and uses a combination of field monitoring and ANSYS/LS-DYNA 3D finite element numerical simulation to analyze the characteristics of surface vibration hollow effect under the liaison channel blasting excavation and predict its attenuation law. The results indicate that where the surface vibration speed is significantly greater than the unexcavated area, there is a “cavity effect”; with the increase of the longitudinal distance between the mass point and the source of the explosion, the cavity effect amplification coefficient increases rapidly until the extreme value and then slowly decreases. Along both sides of the channel with the increase in distance, the amplification coefficient decreases, the effect of the cavity effect is weakened, at a distance of 8 m from the source (6 m behind the palm surface) to reach the maximum, 2−8 m from the source of the cavity effect should focus on vibration monitoring within the surface area. The excavation area with the blasting conditions is related to the coefficient of 58.52, and vibration attenuation coefficient of 1.43, while the unexcavated area of 152.09, and vibration attenuation coefficient of 1.74, the absorption coefficient of the layer media are 0.019, 0.023, respectively.