At exactly 7:00 a.m. on April 4, 2018, following the commander’s order, the blasting demolition of the old Xi’anmen Bridge in Quzhou City, undertaken by our company, was successfully completed. The newly constructed bridges on both sides, as well as surrounding buildings and key facilities, remained completely unaffected.

The old Xi’anmen Bridge is located across the Qujiang River in an east-west direction in Kecheng District, Quzhou City. It was a 7-span, 45-meter-span, through-type reinforced concrete double-curvature arch bridge. The bridge had a total length of 337 meters, a width of 24 meters, and four lanes for two-way traffic.

In recent years, inspections have shown that the overall technical condition of the bridge was below the required standard, and the load-bearing capacity of the bridge structure could no longer meet the requirements of the original design.

As a major transportation route in Quzhou City, the demolition project faced extremely complex blasting conditions due to the traffic demands of the area. At the time of blasting, the two newly constructed bridges on the north and south sides of the old bridge were already completed and open to traffic. The closest distance between the new and old bridges was only approximately 0.5 m. Pipelines beneath the new bridge, including water supply, natural gas, telecommunications, and power lines, crossed the Qujiang River. The nearest residential communities to the east and west sides were only 130 m and 215 m away, respectively, making the blasting environment highly challenging.

These complex conditions required strict control of the single-shot explosive charge during the demolition of the old bridge. The fractured bridge components after blasting had to collapse vertically, and during the collapse process, it was also necessary to ensure that the mass of structural components simultaneously impacting the riverbed was kept within safe limits.

Based on the numerous stringent objective conditions and technical requirements, our company adopted a combination of deep-hole and shallow-hole blasting techniques, together with zoned and sequential millisecond-delay initiation methods, for the demolition design of the old bridge. By destroying the load-bearing support points of each bridge span, the structure instantly lost its support, allowing each span to collapse and disintegrate individually onto the riverbed.

To reduce the impact of blasting vibrations, collapse-induced vibrations, and blasting flyrock on the two new bridges and surrounding buildings, effective control measures were implemented through the technical approaches of “more drilling, reduced explosive charges, and precise delay timing.” In addition, three safety protection measures were adopted: active protection of the blasting structure, isolation protection between the old and new bridges, and passive protection of the new bridges, effectively minimizing the adverse effects of the blasting operation.

The pre-embedded explosive charging points were arranged at the arch legs, diagonal braces, arch crowns, and bridge piers. A total of 2,650 blast holes were drilled, with 2,010.4 kg of explosives actually used. For the initiation system, high-precision waterproof detonators were employed, with 27 independent blasting zones arranged spatially and 9 delay intervals set temporally, resulting in a total delay duration of 1.42 seconds.

With the commitment of “contributing to urban development and serving the people of Quzhou,” and adhering to the principle of “safety first, quality foremost,” our company successfully completed the blasting demolition through advanced technical design and meticulous blasting operations.

After nearly six months of technical discussions and finalization of the demolition plan, followed by nearly two months of on-site construction, the project was successfully carried out under extremely complex environmental conditions. While ensuring the safe blasting demolition of the old bridge, the operation also guaranteed that the two newly constructed bridges, surrounding buildings, and critical facilities remained intact.

The successful completion of the blasting project received unanimous recognition and praise from the Quzhou Municipal Government, relevant authorities, the project owner, and local residents.