China News Service, Nanjing, June 30 (Reporter Zhu Xiaoying) The countdown for the Shanghai-Sutong Yangtze River Highway Railway Bridge to open to traffic. Let's take a look at the "world record" set by this "steel dragon" lying across the Yangtze River.
On the afternoon of June 30, aerial photography of Shanghai-Sutong Yangtze River Railway Bridge. Photo by Tuobo
Body length: the largest span of the cable-stayed bridge in the world
The Shanghai-Sutong Yangtze River Railway-Railway Bridge, a railway-railway joint bridge across the river is 5827 meters long. The main channel bridge has a main span of 1092 meters, which is the largest span cable-stayed bridge in China and the largest span public-rail cable-stayed bridge in the world. Its opening to traffic will mark the main span of the world's bus-rail cable-stayed bridge entering the "kilometre" era.
According to experts from the China Railway Bridge Bureau, before the construction of the Shanghai-Sutong Yangtze River Railway Bridge, the largest span of the same type of bridge in the world that has been built and under construction is only 630 meters.
The Shanghai-Sutong Yangtze River Express Railway Bridge runs from Nantong in the north to Zhangjiagang in the south. The bridge site is close to the estuary of the Yangtze River and the river is 6 kilometers wide. There are more than 10 docks and ports near the bridge. The daily traffic on the river exceeds 30,000, and the shipping is extremely busy. This requires the main span of the bridge to exceed 1,000 kilometers.
On the afternoon of June 30, aerial photography of Shanghai-Sutong Yangtze River Railway Bridge. Photo by Tuobo
Rooted: The foundation volume of the sinking well is the largest in the world
The main span is 1092 meters. If you want to "stride stably", you must "stand up". The main pier steel sink is the key to this "span".
According to Yan Zhigang, deputy chief engineer of the construction headquarters of the Shanghai-Hong Kong Yangtze River Bridge, the bridge sink well foundation is large. The main tower pier sink well surface is equivalent to the size of 12 basketball courts, with a total height of 110.5 meters, which is the world's largest volume sink well foundation.
To this end, China Railway Bridge Bureau invented the floating-assist structure and the inflation and pressurization system, which realized the overall manufacture, overall docking and overall floating transportation of the steel sink. By closing part of the sinkhole well and inflating the closed wellhole, the giant steel sinkhole is like a fish with a “fish swim bladder”, which can not only float by itself, but also adjust the draught depth and spatial posture during floating transportation.
In order to fix the "big Mac" steel sink well accurately at the design point, the China Railway Bridge Bureau pioneered the "large-diameter anchor pile concrete gravity anchor" program: standing eight steel piles with a diameter of 3.5 meters At the upstream and downstream of the steel sink, four concrete side anchors were dropped on both sides of the north and south. The computer-controlled multi-directional synchronous rapid positioning technology was introduced. Through intelligent equipment, the efficiency and accuracy of positioning were greatly improved, and the steel cable was effectively The connection of the steel sink well achieves the purpose of jointly fixing the steel sink well, and solves the problem of precise positioning of the steel sink well under the action of a thousand-ton water flow.
On the afternoon of June 30, aerial photography of Shanghai-Sutong Yangtze River Railway Bridge. Photo by Tuobo
Height: The main tower of the cable-stayed bridge is the highest in the world
The cable tower is the key force-bearing structure of the cable-stayed bridge. The larger the span of the cable-stayed bridge, the higher the tower height. The main span of the Shanghai-Sutong Yangtze River Public Railway Bridge is 1092 meters, and the height of the main tower rises to 330 meters, which is equivalent to the height of 110 floors. It is the main tower of the world's tallest railway-rail dual-use cable-stayed bridge.
The soaring main tower has brought difficulties to the construction. For concrete, the greater the strength, the higher the label, which means the greater the viscosity, just like the thick porridge has poor fluidity, and it is difficult to pump it to high altitude. In addition, under ordinary engineering environments, concrete sprinkling, heat preservation, and moisture retention are relatively easy, and concrete crack resistance is easily guaranteed, but these are difficult to achieve at an altitude of more than 300 meters.
To this end, by adjusting the mix ratio, China Railway Bridge Bureau developed a new type of concrete, which solved the problems of difficult pumping and non-crack resistance in one fell swoop.
China Railway Bridge Bureau also introduced the real-time monitoring technology for ultra-high concrete main towers. During the simultaneous construction of the tower and beam, the system can realize real-time measurement of the deformation of the tower during the whole construction process to obtain the deformation curve of the tower. Once the detected curve shifts, the builders can immediately correct the deviation to ensure that the main tower is tall and tall according to the predetermined "route" and not "deviation".
On the afternoon of June 30, aerial photography of Shanghai-Sutong Yangtze River Railway Bridge. Photo by Tuobo
Bones: the world's leading strength in new materials
Faced with the need for large spans and heavy loads, the main structural materials of the bridge-steel beams and cables-must be exceptionally "solid".
The steel beams of the main bridge must be "rigid and flexible": they must have sufficient stiffness to meet the load requirements of the bridge's 6-line highway and 4-line railway. The steel beam must also have a certain flexibility, so that under a sudden pressure, the micro-deformation can disperse the pressure and return to normal after the heavy object passes.
From a structural point of view, the steel beam is like a giant "pole". The beams of the two main towers are like the shoulders of a "carried husband". The farther apart the "husbands" are, the heavier the steel beams are loaded, and the easier it is for the "shoulders" to bend and deform downward. Therefore, it is necessary to have a strong cable to hold this "arm".
To this end, the bridge uses 2000 MPa class parallel steel cable stay cables. This is the first time this product has been successfully developed and applied in engineering worldwide, and it has reached the international leading level overall, providing an example for the application of such cable stays. At the same time, the 500 MPa high-performance bridge steel manufacturing technology used in the bridge was first applied to domestic bridge construction, and this technology reached the international leading level.
In order to reduce the impact of beams on navigation, the bridge innovatively uses large-segment hoisting of the main bridge steel beam, which can reduce the workload of on-site welding and hoisting by half. Due to the maximum lifting weight of the steel beam of the entire section of the main channel bridge reaching 1744 tons, China Railway Bridge Bureau independently developed the world's first 1800-ton walking beam crane with the design of "double crossbeam three lifting points" to ensure that the steel beam can be stable Hoist. (Finish)