Numerical Simulation of the Vibration Response of, and Damage to, a Deep Foundation Pit Under Multiple Blasting Events

To address the disturbance and damage to the surrounding rock and retaining piles caused by blasting excavation in deep foundation pits, the vibration response and cumulative damage under multiple blasting events were investigated through numerical simulations. Based on the deep foundation pit project associated with Huicheng Road Station on the Qingdao Metro, ANSYS/LS‐DYNA software was used, combined with the complete restart technique to simulate the multiple blasting excavation process. The vibration response and propagation trends, as well as the damage characteristics of the surrounding rock and retaining piles, were investigated. The results show that the vibration velocity of the strongly weathered rock layer of the surrounding rock in the deep foundation pit decreases in an approximately exponential manner down the height of the foundation pit. However, due to the elevation‐amplification effect, the vibration amplitude first decreases and then increases. The vibration velocity on the blasting side of the retaining piles is dominated by the component in the direction of propagation of the blasting stress wave. The vibration velocity at the top of the pile is low, but the vibration frequency is high. The maximum peak vibration velocities of the surrounding rock and retaining piles are both located near the blasting excavation surface. The higher the peak vibration velocity, the larger the degree of damage. Therefore, it is necessary to optimize the blasting parameters in a timely manner and implement vibration isolation measures to control the blasting vibration velocity and enhance the stability of the foundation pit.