The emergence of the Shanghai-Tong Yangtze River Bridge has once again refreshed the global record, which is known as the "infrastructure madness"!
In terms of steel consumption for the entire bridge project, it has reached 480,000 tons! In this way, the amount of steel used in the bridge can build 12 "bird's nests". The 2.3 million cubic meters of concrete used could also build eight National Centre for the Performing Arts.
From these various data, we can see that the Shanghai-Tong Yangtze River Bridge is difficult, and in the construction process, there are also many thorny problems such as caissons.
The main tower of the Shanghai-Tong Yangtze River Bridge is 330 meters high, which is equivalent to 110 floors when converted into building height. If you stand on the top of the main tower of the bridge and look at the giant ship on the river, it is also like a boat.
But why is it built so high? It turned out that the designer considered that the location of the bridge is located in the lower reaches of the Yangtze River, which is the only way for Shanghai and the Yangtze River estuary area.
In order to ensure that large ships can pass through the bridge unimpeded, the Shanghai-Tong Yangtze River Bridge adopts a cable-stayed scheme, and the distance between the bridge deck and the river surface is set at 70 meters.
But what does this have to do with the height of the main tower? In fact, in the cable-stayed bridge scheme, the main tower is a very critical part of the force, the larger the span of the cable-stayed bridge, the higher the main tower will be built in order for the main tower to support the greater weight.
In this case, the Shanghai-Tong Yangtze River Bridge has set a new record with its 330-meter-high main tower, becoming the world's tallest main tower of the road-rail bridge. So what does the main tower of the bridge rely on to stand firm in the river?
Everyone is happy that the main tower of the bridge is now a world record-holding project, but breaking the world record is no easy feat. The amount of steel used in the main tower of this bridge is 110,000 tons, and the amount of concrete poured is even higher to 730,000 square meters, which is the first in the history of bridge construction in the world!
In addition, the requirements for the construction quality of the bridge are also extremely high, according to the requirements of the plan, the bridge must be able to withstand the 14-level typhoon, the strength of the 8-level **, and the 100,000-ton ship impact.
Therefore, from the time the foundation of the main tower was laid, everyone was nervous and did not dare to slack off a little. Under normal circumstances, most of the bridges will be built in the form of pile foundations, but considering the large span of the Shanghai-Tong Yangtze River Bridge, the height of the main tower, and the weight of the load, the builders can only replace it with other methods.
After a long discussion, it was finally decided to be a caisson plan. The steel caisson of the main pier is 44 meters high, which is then connected to 115 meters with concrete. After all the installation was completed, it was inserted dozens of meters from the bottom of the river.
However, the implementation of the caisson plan did not go smoothly after that, and there were many unexpected situations. But before that, we can't help but think about the question, why did the designers finally choose the caisson scheme to implement?
Steel caisson is a professional term, in fact, it is the pier foundation of the Shanghai-Tong Yangtze River Bridge. The main reason for choosing caisson to exclude piling is the actual local situation. The foundation of the bridge is sandy, and if the piling method is used, the pile body must pass through the sand and reach the rock layer.
But this is the ideal state, if the construction begins, the pile body is still a sand layer after two or three hundred meters, and you have to continue to go down, but in the end, you can't find the rock layer when you break through the edge, then the amount of work done before is in vain.
Considering the specific environment, workload and other comprehensive factors, the final decision is still the "caisson plan", and the caisson foundation of the Shanghai-Tong Yangtze River Bridge is the largest in the world.
The "combined foundation" of steel shell and reinforced concrete, which can be as large as 12 standard basketball courts, such a huge workload, is mainly to ensure that the bridge can not have any accidents in the face of typhoons below level 8 and below level 13 after completion, and safety and quality are always put in the first place.
But even if it is such a large-scale 15,000-ton steel caisson that is rare in the world, why did it deviate during the construction process?
In fact, before the actual installation, the design team took this into account, so the Nanjing Academy of Water Sciences conducted many experiments in response to this question. The results of the complete channel erosion show that the sediment erosion is basically in 25-7.5 meters, the largest is also up to 112 meters, which will not exceed this maximum.
At the time of installation, the relevant professionals updated the data every day and found that the cross-section of the caisson was relatively large, and the horizontal force was also very large. After a period of measurement and estimation, the data show that the caisson will be subjected to a maximum horizontal force of more than 700 tons.
In order to prevent other unnecessary risks, the construction team drove a diameter of 3The 5-meter-long steel pile and the gravity anchor are on the "big guy" with a weight of 900 tons, which can be said to have avoided all risks as much as possible.
But in this case, there are still accidents. The overall construction area of the bridge is located in the lower reaches of the Yangtze River, with tidal fluctuations and turbulent water speeds, and the average flow rate can reach 2 per second5 meters.
Some of the sediment accumulated in the upper reaches of the riverbed was directly carried away by the speed of the river, and the caisson at the bottom began to tilt continuously.
One of the most important aspects of bridge construction is rigor, the approximate deviation will be estimated at the time of design, and it must not exceed this range in actual operation.
The caisson of the Hutong Yangtze River Bridge is to penetrate into the riverbed with a depth of 23 meters, in addition to ensuring that the caisson at the bottom of the river is parallel to the bridge deck, no matter which position, the deviation between the two should be within 75 centimeters. Otherwise, the upper part of the bridge will be greatly affected.
But what happens now?
The engineers of the project held a collective meeting, and after many days, it was finally decided to use the method of local load correction to see if it could be effective.
Generally speaking, it is to pump water on the low side, inject water on the high side, and after adjustment, throw some sandbags and stones around the outside of the caisson, and throw some gravel on the low side of the wellbore, etc., the purpose of these projects is to slow down the speed of sediment erosion.
Once the situation is under control, the caisson can be straightened. First of all, the sediment deposited at the bottom of the high-side caisson should be sucked out, and then some concrete should be poured into the inner wall of the caisson to increase the weight of the inclined caisson and then press it down.
The previously thrown gravel will naturally reach the bottom, so that the inclined caisson can be smoothly supported. At the time of the work, the caisson had already experienced a deviation of 13 metres.
After more than a month of work, the caisson was successfully restored to a stable state in the riverbed, reaching the original precise positioning of the bridge design team.
Once the foundation is complete, work on the upper part of the bridge begins, so how does the main tower, like Optimus Prime, reach the height of the sky?
The structure of the main tower of the Hutong Yangtze River Bridge is complex, and the amount of construction is also very large in operation, so the project team used the hydraulic automatic climbing formwork system without tower crane, and the construction time was further shortened under the condition that the large tower crane could be reasonably laid out.
According to relevant statistics, in recent years, when we have built some large-span bridge towers in China, the approximate daily construction speed is 035-0.4 meters, which is actually very fast, but the Shanghai-Tong Yangtze River Bridge, as a world-class project, is certainly not matched by these.
The main tower of the 330-meter-high Shanghai-Tong Yangtze River Bridge took two years to complete, and according to this time, the construction of the main tower of the Shanghai-Tong Yangtze River Bridge is 044 meters! It directly refreshed the record for the fastest construction of the high-altitude main tower.
After the completion of the construction of the bridge, all parties are also extremely concerned about it and look forward to using it as soon as possible, but before the official opening of the bridge, some tests must be carried out in accordance with the process.
In the early morning of May 28, 2020, the bridge load test of the Shanghai-Tong Yangtze River Bridge in its main channel was successfully completed, which was the result of all the staff's all-night hard work.
The results of this test are also very amazing, and the total weight of the load has reached almost 9,000 tons, which is the largest weight of this test in our country.
On July 1, 2020, the Shanghai-Tong Yangtze River Bridge was finally officially opened to traffic. And there is also a high-tech product on the bridge deck.
On the entire highway of the bridge, there is the coverage of Huawei's new 5G micro-station, and the coverage of Zhongtian's new 5G leaked cable is used in the railway surface, and the part of the approach bridge is supplemented by multiple ultra-high-speed rail tower sites built by Nantong Tower.
From this, we can see what is called real bridge intelligence. Luo Bing, the manager of the project department, also introduced that the project has had many innovative achievements in the six years from its establishment to completion, including more than 30 patents and more than 20 invention patents.
The Shanghai-Tong Yangtze River Bridge is a very representative project in China. Although this process was like a sudden accident like the tilt of a 15,000-ton steel caisson, the whole team was not intimidated by this difficulty, and everyone began to think about how to solve the project more properly.
The bridge is our milestone treasure, but the spirit behind the bridge is also worthy of our attention and praise, it is so many people with lofty ideals, our country can have more achievements and development in infrastructure development.
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