Jiangyin Yangtze River Highway Bridge toll station is located on the north bank of the bridge, with a total of 32 toll stations. Expressway, the northern connecting line of Jiangyin Yangtze River Bridge, is the first six-lane expressway in northern Jiangsu.
Jiangyin Yangtze River Highway Bridge is a key construction project during the Ninth Five-Year Plan period, and it is a river-crossing "throat" project of Tongjiang-Sanya national highway trunk line and Beijing-Shanghai national highway trunk line in the national "two vertical and two horizontal" highway skeleton.
The bridge is designed according to the six-lane expressway standard, with the designed running speed of 100km/h, the deck width of 33.8m and the navigable clear height of 50,000-ton Panamanian bulk carrier. The project started construction on June 22nd 1994 and 165438, and was successfully completed and officially opened to traffic on September 28th 1999. The final account of the project is 2,729.96 million yuan, saving 644.04 million yuan compared with the estimated 3.374 billion yuan, and the construction period is 55 days ahead of schedule, which benefits the bridge itself by 26 million yuan in advance. Suspension bridge structure
Jiangyin Yangtze River Highway Bridge, suspension bridge structure. The main span is1385m. Portal reinforced concrete tower column, height193m, with three beams inside.
The main cable of suspension bridge is the most important load-bearing component of the whole bridge, and its length and line shape have a decisive influence on the geometry of the whole bridge. The main cable of Jiangyin Bridge is fabricated by precast parallel strand method (PPWS). Each strand consists of 127 high-strength galvanized steel wire, with a diameter of 5.35mm, a strength of 1.600 MPa and a weight of 50t. The cable strand length is 2 180m, and sleeve-type thermal spray anchors are used at both ends. The anchor cup is made of cast steel, and zinc-copper alloy is poured inside. After the steel strand is processed in the factory, it is wound on the reel and transported to the construction site. The main cable of the main span consists of 169 strands and ***2 1 463 steel wires. The side span is 8 strands more than the main span. The diameter of the main span cable is 876mm, and the diameter of the side span cable is 897 mm. The main cable is made of high-strength galvanized steel wire16800 t. The suspension cable system of Jiangyin Bridge is mainly composed of cable clamps installed on the main cable, slings installed on the steel box girder and ear plates. The sling spacing is 16m. For slings with a length greater than 10m, parallel steel wire strands with a diameter of 5mm are used, while for slings with a length less than 10m, steel wire ropes with a diameter of 80mm are used. This kind of steel wire rope has good flexibility and is suitable for short slings with high rigidity. When the steel wire of the main cable passes through the top of the tower and enters the saddle for decentralized anchorage, it will exert great pressure on the concrete, so it is necessary to set the saddle and loose cable saddle. In Jiangyin Bridge, all these components are cast-welded components, the weight of each saddle (including the bottom plate) is 172t, and the loose cable saddle is 78 t ... During the installation of the main span steel box girder, the sag of the main span cable changes constantly, which makes the inclination of the main cables on both sides of the main tower change and the horizontal force is not equal. This horizontal force difference will produce a great bending moment at the root of the main tower, so during the erection of the main cable, the position of the moving saddle will adjust the inclination angle of the main cable and reduce the bending moment at the root of the main tower.
As the main girder of the bridge deck, the flat closed streamlined section is adopted. The selection of main girder section is finally determined by segmental wind tunnel test. The height of the beam is 3m, and the total width of the beam is 36.9m, in which the bridge deck is 29.5m wide, and the tuyeres on both sides are 1.5m wide. Sidewalks, railings and maintenance vehicle tracks are set outside the tuyeres, and each side is 2.2m wide. The steel box girder of the whole bridge is divided into 87 sections, with a total weight of18,000t. The standard girder length of each section is 16m, the mid-span length is 18.2m, and the girder length of both ends is 9.33m. The hoisting section is 32m long, that is, it is assembled by two standard sections and then hoisted. The box girder adopts orthotropic structure of British alloy steel. The thickness of the roof is12mm; ; The thickness of the bottom plate is10mm. The spacing between partition boards in the box is 3.2m, and the stiffening groove ribs are rolled by 6mm thick steel plates. Lighten the weight of steel box girder to reduce the tension of main cable and the load of anchorage.
Manufacture of steel box girder
The fabrication of steel box girder adopts factory prefabricated stiffening plate unit of top and bottom plate, diaphragm and corner unit of air nozzle, and then it is transported by water to the assembly yard jig less than 1km from the bridge site to assemble box girder segments. The jig frame considers welding deformation and installation pre-camber, which ensures the good consistency of high-altitude welding of steel box girder. The hoisting of steel box girder is to lift the steel box girder segment transported by barge from the water surface to the design height with hydraulic cable crane and fix it in place with slings. For the butted North-South Section 3, because the water is shallow, it can't be hoisted directly, so the hoisting method is adopted. Both the inside and outside of the steel box girder are painted, but due to the closed ventilation of the box body and the dehumidification system, the air humidity is kept below 40%, which greatly delays the corrosion of the steel plate. The south tower foundation adopts rock-socketed bored piles with a diameter of 30m and a length of 35m, and the pile cap is poured on the top of the pile. Pile foundation and cap concrete * * * is1.1.50000 m3. The south anchorage is located on the mountain. Because of the development of lithologic joints, gravity rock-socketed anchor is adopted. The front edge of the anchor seat is made into an inclined plane with a tooth ridge to increase the sliding resistance.
The overburden of the North Tower is 80m thick. With the depth deepening, the saturated soft soil layer with poor consolidation degree gradually changes from soft loam and silty sand to dense gravelly medium-coarse sand. The pile group foundation consists of 96 cast-in-place piles with a diameter of 2.0m, with an average pile length of 85m. In order to reduce the plane size of pile caps, the minimum pile spacing is adopted in the code, and the inclination of piles is limited to 1/200. For such a difficult group pile foundation construction, the approach bridge pile foundation is used in the project to carry out the process test first, and two test piles are made to determine the bearing capacity of a single pile, so that the original design of the North Tower 123 pile is reduced to 96 piles, which saves investment and speeds up the progress. The amount of concrete for pile caps and piles reaches 50,000m3. The cover thickness of the north anchor is100m. Within 40m below the ground, it is mainly composed of loose fine sand and loam, and gradually reaches a dense fine sand layer; 40-50m below the ground is a hard clay layer with medium-coarse sand mixed with dense gravel. North anchorage structure is one of the key parts of the bridge. In the design, shallow buried foundation, medium buried enlarged foundation, pile group foundation and underground continuous wall are compared. Finally, the open caisson foundation with the size of 5 1mx69m was selected. The open caisson is divided into 36 sections, the open caisson is 58m high, with * * 1 1 section, and the bottom section is 8m high.
The sinking elevation of the open caisson is -55.6m, and the top elevation is 2.4m m. In order to ensure the balance of the anchor body, after the open caisson sinks in place, the bottom is sealed, and water is injected into the third row (near the north tower side) 18 warehouse in front of the open caisson. The middle two *** 14 warehouses in the fourth, fifth and sixth rows are filled with sand, and the sixth row.
The North Anchorage is a structure mainly bearing horizontal force, which bears the tensile force of two main cables of 640MN and transmits it to the open caisson and foundation. During the whole construction and operation, the stress of open caisson is constantly changing. Under these loads, the open caisson foundation is subjected to uneven pressure and settlement occurs. Therefore, before the erection of the main cable, in order to reduce the backward inclination of the open caisson, the concrete block at the rear edge of the anchorage will not be poured for the time being, and the anchorage block will be poured after the stiffening beam is erected. The design allows the anchor pier to move forward horizontally 100mm, and the actual horizontal displacement since opening to traffic is less than 25mm.
Like the North Tower, the South Tower is a portal frame reinforced concrete structure with two columns and three beams, which mainly bears vertical loads from cable saddles, lateral wind loads and earthquakes. The tower column is a double-chamber box structure, and the two rooms are equipped with a maintenance elevator and a maintenance elevator respectively. The beam is also a double-chamber box-type prestressed concrete structure with a height of 1 1m, and the lower beam supports the main beam and the side-span concrete box girder. The tower body is constructed by climbing formwork, and the north tower climbs 6m at a time (the south tower climbs 4.5m). In order to facilitate steel binding, formwork erection and measurement control, rigid skeleton positioning is adopted. After the pouring height of the tower exceeds a certain height of the beam top, the beam is poured with a steel pipe template with a diameter of 900mm, which is poured twice and tensioned twice. The towers and beams of the South Tower and the North Tower are made of 6,543,800 m3 concrete. In the competition of bridge type scheme design, considering the stability of bridge tower, its influence on shipping, construction difficulty and investment saving, the span layout of main bridge was finally selected as (336.5+ 1, 385+309.34) m.
The length of the whole bridge is 3071m; ; The main span is a single-span simply supported steel suspension bridge, and the main cables on both sides are straight-pulled. The side spans are all prestressed concrete continuous beams. For the south span, consider avoiding the ancient fort of Jiangyin fortress, which is a cultural relic to be protected. Three-span continuous beam with 2×60m+40m is adopted.
The clear distance between the North Anchorage and the Yangtze River levee is more than 200 meters, which ensures the stability of the levee during construction. The north span is 50m+70m+50m+3×50m continuous beam, and the beam height of the side span is the same as that of the main span. The north approach bridge adopts 500m and 30m prestressed simply supported T-beams, with a longitudinal slope of 3% and a slope length of 1 1,500m ... Every increase of 10mm in deck pavement will increase the load of 10000 kn and increase the north anchorage pressure.
The pavement of Jiangyin Bridge adopts 48 mm thick cast asphalt concrete (asphalt horseshoe fat). The poured asphalt concrete is paved twice, and the surface is covered with stones with asphalt particle size of 14mm, which are gently rolled to ensure the surface smoothness. The bottom layer is asphalt rubber base layer as waterproof layer, adhesive base layer composed of soluble rubber asphalt and antirust layer coated with epoxy zinc-rich paint on the surface of steel plate. Asphalt concrete pavement of steel bridge deck should solve the problems of high temperature stability, low temperature crack resistance, normal temperature fatigue resistance and interlayer adhesion. Therefore, through a large number of experiments, materials and proportions are selected to meet various properties and indicators.