Introduction of Chongqing Yuzui Yangtze River Bridge?

Chongqing Yuzui Yangtze River Bridge is a super-large bridge project across the Yangtze River in the eastern part of expressway, the outer ring of Chongqing, and it is an inter-provincial highway passage in the western development. The bridge starts from Sunflower Villa in Yangguang Town, crosses the Yangtze River near Shipandong on the south bank of the Yangtze River, lands at Shimutan on the north bank of the Yangtze River, and ends at Xiaguoyuan in Yu Zui Town. The bridge is a suspension bridge, with a total length of1.440m and a main span of 61.6m, which is the key control project of expressway in the outer ring of Chongqing. The whole project was completed and opened to traffic in April 2009. The drive from Yang Guang in Nan 'an District to Yu Zui in Jiangbei District has changed from 1 hour to less than 5 minutes. Yuzui Yangtze River Bridge is designed as a two-way six-lane bridge with a speed of 100 km per hour. There is an overpass at the north bridge head, which spans the Huai Yu Railway. The design base period is 100 year.

general situation

Yu Zui Liangjiang Bridge is a dual-purpose bridge on the Yangtze River, located in Yu Zui, Jiangbei District, Chongqing, and connected to Mingyuetuo in Banan District in the south. The bridge is a river-crossing passage in the east half ring of Chongqing Ring Expressway, with a total length of1.438m.. Two-way six lanes, completed and opened to traffic on June 65+February 36, 2009. When the bridge was built, it was named Yuzui Yangtze River Bridge, because the North Bridge Head is a Liangjiang New Area vigorously built in Chongqing, and the bridge was renamed Yu Zui Liangjiang Bridge.

Yuzui Yangtze River Bridge is a control project in the eastern section of expressway, the outer ring of our city. Total length1.438m, two-way six lanes, monolithic subgrade width of 33m, design speed 100km/h, and bridge deck speed is the fastest in our city at present, with main span of 616m (longer than Egongyan Bridge16m).

The whole bridge of Yuzui Yangtze River Bridge consists of 52 steel box girders with a total weight of about 9390 tons. The "0" block in the middle section was hoisted for the first time yesterday. The beam is 3m high, 36.8m wide, 12.5m long, weighs about 200 tons and has a hoisting height of 70m.

Yuzui Yangtze River Bridge is a super-large bridge project across the Yangtze River in the eastern section of expressway in Chongqing's outer ring, and it is an inter-provincial highway passage in the western development. The bridge starts from Sunflower Villa in Yangguang Town, crosses the Yangtze River near Shipandong on the south bank of the Yangtze River, lands at Shimutan on the north bank of the Yangtze River, and ends at Xiaguoyuan in Yu Zui Town. The bridge is a suspension bridge with a total length of1.440m and a main span of 61.6m. It is the key control project of expressway in the outer ring of Chongqing.

The whole project was completed and opened to traffic in April 2009. The drive from Yang Guang in Nan 'an District to Yu Zui in Jiangbei District has changed from 1 hour to less than 5 minutes. Yuzui Yangtze River Bridge is designed as a two-way six-lane bridge with a speed of 100 km per hour. There is an overpass at the north bridge head, which spans the Huai Yu Railway.

In Loulou Village, Yu Zui Town, Jiangbei, a 200-ton steel box girder was hoisted into the air from the river. On the same day, Yuzui Yangtze River Bridge officially hoisted the steel box girder.

The Yuzui Yangtze River Bridge, an important node project of the Outer Ring Expressway, was officially hoisted yesterday. According to the introduction of the construction unit, the hoisting construction is expected to last for two months, and the fishing mouth section of the Yangtze River is closed for three hours every day114. It is reported that the main bridge of Yuzui Yangtze River Bridge is expected to be completed by the end of the year.

Building structure

Chongqing Yuzui Yangtze River Bridge is a single-span simply supported steel box girder suspension bridge with a middle span of 6 16m and a north-south side span of 180m and 205m respectively, which is a sling-free area. In the design state, the theoretical midspan sag is 6 1.6m, and the vertical span ratio is 1∶ 10. The center distance of main cable is 34.8m, and the sling spacing is12.0m. The south anchorage adopts embedded concrete gravity anchor body, which is rectangular to expand the foundation, and the center elevation of loose cable saddle is 237.5m. The north anchorage adopts triangular frame concrete gravity anchor body, which is rectangular to expand the foundation, and the center elevation of loose cable saddle is 225.0m The south tower adopts reinforced concrete multi-storey portal frame and tower. There are 9 φ2.5m cast-in-place piles at the bottom of each tower column.

The tower of the North Bridge adopts reinforced concrete multi-storey portal rigid frame, and the tower column is a rectangular single box and single room structure with variable wall thickness, with three beams. There are 9 φ3.0m cast-in-place piles at the bottom of each tower column. The main cable adopts precast parallel stranded wire method (PPWS). Each main cable has 65 strands, and each strand contains 127 φ5.2mm galvanized high-strength steel wire. The void ratio at the cable clamp is 17%, the void ratio outside the cable clamp is 19%, and the corresponding outer diameters of the main cables are 5 19mm and 525mm respectively. The stiffening girder is a flat streamlined steel box girder with orthotropic slab bridge face, with a height of 3m and a total width of 36.8m The upper part of the south approach bridge is composed of two prestressed concrete continuous box girders with equal section of 6×35m. The lower foundation adopts a single row of two φ 1.7m bored piles, and the piers are rectangular solid piers. The upper part of the north approach bridge is composed of two prestressed concrete continuous rigid frames with equal sections of 4×56m and 3×56m. The lower foundation adopts two rows of four φ 1.8m bored piles, and the piers are hollow rectangular sections.

Third, characteristics

1. Anti-collision measures for the north tower. During the construction of the bridge, the North Tower was located on the shore. During the operation of the bridge, due to the impoundment of the Three Gorges Dam and the water level in the Three Gorges reservoir area175-145-175, the north tower is in danger of being hit by a ship. In order to resist ship collision, the tower column of the north tower below the elevation of 203 meters adopts rectangular solid section, and a bottom beam is added to the lower tower column, and the beam adopts box hollow section. The design idea is that when ships collide, considering that the tower column is the main stress component of the bridge, it is not allowed to be damaged at all, so the tower column adopts solid section to ensure the safety of the tower column after being hit; The bottom beam is not the main stress component of the bridge, and its main function is to strengthen the lateral connection between the two towers and increase the structural stiffness. Therefore, the bottom beam adopts box-shaped hollow section, even if it is damaged by ship collision, it can be repaired in time without affecting the structural safety. The advantage of the above design is to minimize the material consumption and reduce the project cost on the premise of ensuring the normal use function of the bridge. In addition, in order to improve the ductility of concrete and enhance the anti-collision ability, fiber concrete is used for the solid section and bottom beam of the North Bridge Tower.

bridge

2. Design of temperature control for mass concrete of anchorage. The anchorage foundation on the north bank of the bridge is 67m long, 5 1.8m wide and 23.75m high. It is made of C30 concrete and has a volume of 53000m3. The cracks in mass concrete are mainly temperature cracks. In order to control the occurrence of temperature cracks and improve the durability of the structure, the temperature control standard and corresponding temperature control measures without harmful temperature cracks are designed and put forward through temperature stress simulation calculation and combined with previous successful experience. Reduce the pouring temperature of concrete. Control the concrete into the mold temperature does not exceed 28℃. If the pouring temperature is not within the control requirements, the temperature of cement and aggregate should be reduced, and the mixed water should be cooled with a cooling tower, and concrete should be poured at night as much as possible. Control of concrete pouring layer thickness and pouring interval. Because the foundation has a strong constraint on concrete, the layered thickness of the bottom five layers of concrete is not greater than1.2m. In order to prevent the lower layer of concrete from having a strong constraint on the upper layer of concrete, the pouring of the upper and lower layers of concrete should be controlled within 6d, and the temperature difference between the upper and lower layers of concrete should be controlled at 15 ~ 20oC. Temperature difference control between inside and outside of concrete.

The temperature difference between inside and outside is the main cause of surface cracks, and the temperature difference between inside and outside of concrete should be controlled within 25oC. Cooling water pipes are arranged in concrete, and φ42mm×2.8mm cooling water pipes are arranged in each layer of concrete. Set a layer of anti-crack steel mesh on the concrete surface. The temperature sensor is embedded in the foundation concrete to measure the temperature change process in different parts of the concrete, and to test the temperature characteristics and temperature difference standards in different periods. When the effect of temperature control measures is not good enough to reach the temperature control standard, remedial measures can be taken in time, such as increasing the flow of cooling water pipes.

Chongqing Yangtze River Bridge Fish Mouth

3. The use of Zn-Al pseudoalloy protection system. The bridge is located in Chongqing, which belongs to the transitional climate zone from north subtropical zone to subtropical zone, with abundant rain, and belongs to the acid rain zone in China. The pH value of rainwater in Chongqing is generally below 4.0, and it can reach 3.0 in winter. Sulfate ion accounts for 70% ~ 90% of total anions, which is a typical sulfate rain. Moreover, the steel box girder is located on the river, foggy and in a high humidity environment for a long time, and its environment belongs to a heavily corrosive environment. In order to improve the corrosion resistance of steel box girder, the multiple anti-corrosion system of spraying Zn-Al pseudo-alloy+sealing primer+intermediate paint+topcoat is adopted for the first time in new bridge projects in China. Advantages of Zn-Al pseudoalloy coating system. The long-lasting coating anticorrosion system for steel bridges generally consists of three coating (plating) layers with different functions, one layer from the inside out: the first layer is the sacrificial metal bottom layer which can be used for cathodic protection, and its function is to provide electrons by the sacrificial metal, thus ensuring the steel structure from corrosion; The second layer is an intermediate layer for sealing holes and preventing chemical corrosion. The sprayed (plated) metal layer and chemical coating are porous bodies with gaps, and the holes need to be plugged. The al2o 3 network structure formed by spraying Zn-Al pseudoalloy has a certain plugging effect on holes, and ZnO and ZnCl2 _ 2 have a certain plugging effect on Al2O3. The third layer is an anti-aging decorative surface layer, usually a colored filling coating, which can resist ultraviolet rays and infrared rays, reduce the aging of the intermediate layer, and play a smooth and beautiful role.

4. The use of large displacement and multidirectional displacement expansion joints. Suspension bridge is a cable-bearing bridge with small structural stiffness. Under the multiple loads of vehicle live load, temperature load and wind load, the displacement of stiffening beam is the superposition of various displacements, including translation and rotation in all directions, which is very complicated. Many long-span bridges in China, especially the expansion joints of suspension bridges, are damaged to varying degrees. Through careful analysis of the causes of expansion joint damage, it is determined that modular expansion joint can not meet the complex displacement of stiffening beam of suspension bridge. After extensive investigation and study, Yu Zui Bridge finally adopted the modular multi-directional displacement comb tooth joint. The expansion joint can not only meet the displacement of the stiffening beam along the bridge direction, but also meet the vertical and horizontal rotation of the stiffening beam, which well adapts to the complex displacement of the stiffening beam under various loads and improves the driving conditions.

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