Blasting excavation is a critical construction method for enhancing the canal channel expansion efficiency. However, the induced blasting vibration may adversely affect the substructure of existing waterway bridges. To clarify the dynamic response characteristics of the bridge substructure subjected to blasting-induced vibration, this study analyzed the stress and vibration velocity distributions in the adjacent bridge substructure during the Pinglu Canal channel expansion project. A finite element numerical simulation method, validated by field test, was employed to establish the safe vibration velocity threshold for the substructure based on the maximum tensile stress criterion. The results show that the maximum tensile stress occurs at the interface between the bridge pile foundation and the pile cap during canal blasting excavation. The most significant vibrations in the substructure are concentrated in the pile foundation. The allowable vibration velocity for the bridge substructure, with the pile cap as the monitoring point, is 3.2 cm/s.

In the blasting excavation project of the Pinglu Canal channel, the adjacent bridge pile foundation is in a repeated blasting vibration environment for a long time, and its structural damage accumulation effect directly affects the safety performance of the whole life cycle of the bridge. Clarifying the damage evolution mechanism of pile foundations under repeated blasting vibration is a key scientific premise for ensuring the coordinated development of efficient canal channel excavation and the safe operation of adjacent bridges. Based on the channel blasting project for the Luyang New Village Bridge in Pinglu Canal, combined with a finite element numerical model that considers the cumulative damage of the concrete structure, the influence of on-site blasting construction on the pile foundation during construction is simulated and analyzed. Based on the reliability analysis of the model, the cumulative damage variation law of pile foundation under different blasting times is simulated and analyzed. The damage variable prediction model based on the peak vibration velocity of pile foundation is established, and the cumulative blasting times of pile foundation safety under the given blasting center distance are obtained. The results show that the maximum damage variable value of the pile foundation appears on the horizontal side of the explosion source. When the explosion center distance is less than 20 m, the damage to the pile top area is significantly aggravated. The safe blasting times for pile foundations are 2~3 times longer when the blasting center distance is 20 m.