Blasting, Volume. 42, Issue 2, 129(2025)
Research on Blasting Demolition Technology for Partial Spans of Continuous Girder Bridges
The blasting demolition of partial spans in continuous beam bridges frequently entails substantial risks of damage to the adjoining spans. To ensure the effective collapse and fragmentation of the bridge while safeguarding the integrity of adjacent spans, a case study was undertaken focusing on the blasting demolition of a damaged section of a continuous beam bridge in Ankang City. Using ANSYS/LS-DYNA software, numerical simulations were conducted to investigate the impact of water pressure blasting on the upper box girder and evaluate various collapse scenarios for the lower piers. These scenarios included row-by-row inclined collapse, span-by-span collapse, and center-to-both-sides collapse patterns. The optimal blasting scheme was identified by comprehensively evaluating three key parameters: structural fragmentation efficiency, collapse configuration, and induced vibration velocity during demolition. Based on these simulation findings, an optimized blasting design was developed, with subsequent safety verification conducted on the vibration velocities to ensure structural integrity and operational safety. The results demonstrate that implementing water pressure blasting in the upper box girder successfully achieved substantial structural fragmentation while effectively controlling debris dispersion and minimizing potential impacts on neighboring spans. Through a strategic approach involving the conversion of the continuous beam into a supported configuration prior to demolition, coupled with a sequential detonation protocol initiating at the main beams of adjacent spans followed by row-by-row inclined collapse of the lower piers, the proposed scheme successfully achieved controlled bridge demolition. This methodology ensured optimal structural fragmentation while reducing vibration velocities within safe thresholds, effectively protecting adjacent spans. The field implementation results aligned well with the numerical simulations, as evidenced by the controlled collapse process and satisfactory fragmentation patterns observed during the on-site blasting operation. No significant damage was observed in the proximate piers. The peak maximum vibration velocity recorded at the monitoring points in the numerical simulation was 3.58 cm/s, closely aligning with the field-measured value of 3.96 cm/s, demonstrating the simulation results' reliability.
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ZHENG Xuan-rong, REN Kai, LIU Rui, LI Shuai-liang, YUE Xue-ru. Research on Blasting Demolition Technology for Partial Spans of Continuous Girder Bridges[J]. Blasting, 2025, 42(2): 129
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Received: Jan. 22, 2025
Accepted: Jun. 24, 2025
Published Online: Jun. 24, 2025
The Author Email: REN Kai (2022185367@qq.com)