How To Operate This "major Surgery" In Lingqiao? (3)

How to operate this "major surgery" in Lingqiao? (3)

When Lingqiao was being repaired , Bridge Maintenance: A case of changing old riveted nodes to welding. Bridge Maintenance: A case of changing old riveted nodes to welding . There is such a strange and counterintuitive practice, that is, the tens of thousands of nodes connected by rivets on the entire bridge neither use welding nor installation of bolts, but rely entirely on experienced and older riveters to hammer and restore them again and again with hand-held tools. Because the workload of this process is extremely large, it occupies the longest part of the time spent on the entire overhaul.

Narrow space for arch rib installation

The net width of the arch ribs is less than 40 centimeters, but the height reaches 1.7 meters. Workers can only perform manual operations when they turn sideways. During the overhaul of Ningbo Lingqiao, the installation of arch ribs was the first step in structural assembly. Such a small and compact working space required a very high level of accuracy in hoisting and positioning. Even a slight deviation of a few millimeters would not match the corresponding connection holes.

The construction team set up a closed workshop on the side approach of Baizhang Road, and used a gantry crane to lift the arch ribs onto the correction pedestal for reinforcement and riveting. This not only ensures the safety of high-altitude operations, but also prevents the rust removal waste liquid from being directly discharged into the Yongjiang River to pollute the water body.

Synchronous riveting of boom horizontal connection

The three components of the suspenders, arch ribs and cross-links must share the same batch of rivet holes. Therefore, they must be in place at the same time to perform the riveting action. It is absolutely not possible to install one of them first and then reinstall the other one.

When multiple components need to be aligned at the same time and riveted together, the technical complexity is much higher than when only a single component is installed.

Before the formal riveting operation, experienced veteran workers led the workers to pick up rivets of different specifications and perform plug-and-pull tests on the holes of these steel beams one by one. The judgment standard is that only those rivets that can pass through smoothly will be considered to have passed the quality inspection. After all this confirmation work is completed, the subsequent heating and hammering of the rivets will be carried out. The ultimate purpose of this is to effectively avoid the need to rework due to errors on site.

The entire bridge deck is transported and upgraded

The new bridge deck and the corrected and repaired longitudinal and cross beams must be assembled together in the factory to become a single piece, and then transported to the bridge location for repairs on Lingqiao. How does this "major surgery" work? (3), and then carry out the overall lifting and positioning process. The booms and beams here are connected by interpolation. When docking, the dimensional accuracy requirements are very strict, and they must be accurate to the millimeter level. If the deviation is large, it will not be installed on site at all.

Because the construction window in 2026 is very small, the entire transportation and bridge position improvement must be completed at once. As long as there is any deviation in the manufacturing dimensions, the holes will not be aligned on site. In this case, the only option is to take the item back to the factory for reprocessing. This will delay the entire construction period.

The old riveting process returns

In order to preserve the attributes of the cultural relics of Lingqiao, all steel components were spliced ​​using the old-fashioned rivet construction method that appeared at the beginning of the last century. No welding technology or high-strength bolts were used at all.

The master of old-fashioned riveting work personally leads his apprentices in the work. Each rivet must be heated to a temperature of 1,000 degrees, and then the metal structure itself has softened, and then is forced into the reserved hole with a hammer.

When hammering, the force must be even. As long as the rivet head is not hammered properly and shows signs of being crooked or skewed, the connecting parts of the rods will become loose, and the overall steel truss will become unstable. There are tens of thousands of rivets on the entire bridge. If the construction is carried out at normal hand hammer speed, the time spent on disassembly and assembly will take the most time among all the processes of overhaul.

Bridge deck paving and anti-corrosion

After the bridge deck is in place, the asphalt concrete surface layer is laid, and ancillary facilities such as railings and drainage lines are assembled simultaneously. In terms of anti-corrosion treatment, a very advanced coating process is used for the operation. The color of the topcoat is completely consistent with the color before the overhaul. If viewed from a distance, it looks no different from the old bridge.

The foundation reinforcement adopts the prestressed mode. This method allows the old foundation from 1936 and the new reinforcement system to bear the force together. This can not only preserve the original structure, but also improve the load-bearing capacity, and will not additionally change the appearance of the bridge abutment, nor will it have any impact on the navigation under the bridge.

Restoration and opening to traffic

During the construction process, the original appearance of the welding marks and bullet holes left by temporary repairs during the war was preserved. For old booms that can continue to perform their service tasks, all operations will be retained.

For cracks that occur, continue to use them after repairing them. The replacement parts were copied according to the British specifications used in 1936. After the riveting action was completed, the appearance remained consistent with the original bridge.

Since the original structure was found to be damaged during the construction process, it needs to be inspected one by one to determine whether it needs to be replaced. There are many unpredictable situations, so the day when the Lingqiao is reopened to traffic has not yet determined the bridge repair: in the case of changing the old riveted joints to welding , car owners still need to wait a little longer.

Do you think that the old bridge should stick to the riveting process and adhere to the rules of repairing it as before? Or should we simply use welding and bolting methods to improve the efficiency of construction? Everyone is welcome to come to the comment area to chat about what you think. If you think this point of view is quite interesting, don’t forget to give it a like and forward it to your friends who also like to study bridge knowledge.