The lifting of the old bridge of Yihe Bridge on Beijing Road is progressing smoothly!
“Group 1 is starting to lift now, and the on-site personnel should not leave!” “Check the A1 pressure sensor on the 7th pier!”
On November 12, 2021, after setting the jacking height and speed on the console, the operator gave an order, and the fourth day’s jacking work of the old bridge of Yihe Bridge on Beijing Road began.
“We selected a section of the bridge with a length of 300 meters and a weight of more than 4,000 tons as the test section for the jacking test. This section requires 80 hydraulic jacks to work at the same time, observe the problems in the jacking process and solve them in time, so as to provide technical support and data for the subsequent smooth jacking. At present, everything is progressing smoothly.” The construction staff introduced. On the afternoon of November 16, the test section has been jacked up to a height of 2.6 meters, which means that the test section is already 2.6 meters higher than the old bridge. After the test section has been jacked up, the remaining bridges will be jacked up, and finally the old bridge will be jacked up at one time.
The Old Bridge Project of Yihe Bridge on Beijing Road requires 560 hydraulic cylinders to lift the 20,000-ton bridge. The south and north sections of the old bridge are 1,210 meters long and weigh 25,000 tons in total, requiring 560 jacks. If a car weighs 1.6 tons, it is equivalent to using 560 hydraulic jacks to lift nearly 15,000 cars on a plane that is 1,210 meters long and 22 meters wide.
Bridge jacking technology refers to a new type of bridge deviation correction technology that safely lifts the bridge to the required height through jacks and other auxiliary equipment without changing the shape of the bridge. This technical principle is very simple, but the technical requirements are extremely high, and every step is critical.
With high technical requirements, difficult construction, strong professionalism, and tight construction period, how to ensure the first-time success of the jacking work?
In the early stage, the project department prepared a construction plan, including technical preparation, labor allocation, material preparation, safety, quality, environmental protection and other measures. In addition, it has been checked and verified many times, and repeatedly demonstrated by many experts to ensure that there is nothing wrong before the construction can be carried out.
In jacking technology, the first step is the construction of the reaction force foundation. The reaction force foundation can share the load transmitted during the jacking process, and will share the load transmitted by the bridge deck with the old bridge pile foundation later.
Since the beam body needs to be lifted, the pier column must also be “increased”. During the hydraulic jacking period, the jacks lifted the bridge body weighing more than 25,000 tons, leaving room for the “heightening” of the piers. When the pier is “heightened”, the method used is similar to “boning” in medicine. That is, part of the cover beams of the original pier columns are chiseled, the original steel bars are lengthened, the cover beams are heightened, the supports are installed, and the bridge deck falls on the supports to ensure that the old bridge and the new bridge deck are at the same elevation.
The difficulty of this jacking technology is how to keep the upper structure safely lifted to the required height without being “deformed”. “There is a pressure sensor next to each jack to monitor the situation at any time, and instantly transmit the jacking pressure, jacking displacement and other data on the jack to the synchronous jacking control system. Any small error cannot escape the monitoring of the system. Absolutely put an end to the emergence of uncontrollable situations.” The technical director Cheng introduced. The bridge body weighing 25,000 tons was carefully lifted up, and the construction accuracy was like “needle embroidery”. It is a big challenge to control the jacking speed so that it can be lifted evenly and synchronously, and the error needs to be controlled within 0.1 mm. For every 20 cm of jacking, it is necessary to increase the steel support, and check the jack, oil pipe, limiter, sensor, hydraulic synchronous jacking control system and other equipment to ensure that the jacking work is foolproof.
In addition to the many difficulties in lifting, there is also a key point – the seamless splicing of the old and new bridges. The length of the joint between the new bridge and the old bridge is 1240 meters. How to integrate the two into one through seamless splicing is the key technical core of this bridge. For the seamless splicing technology of the new bridge and the old bridge, engineers and technicians will use UHPC (ultra high-performance concrete) materials and seamless splicing technology solutions.
With the precise control of the PLC hydraulic synchronous jacking system, 560 hydraulic jacks can jack up the 25,000-ton bridge within the error range of 0.1 mm. This is a great feat. With the advancement of technology and the subsequent iteration of hydraulic synchronous jacking systems and jacks, similar projects will be completed very easily, and torcstark is working hard to move forward.