Superstructure of cast-in-place continuous box girder of prestressed bridge With the economic growth of our country, people's living standards are constantly improving. China has also continuously increased its investment in highway construction, especially in high-grade highways. Has a large number of bridge construction investment, accumulated construction experience. As a kind of prestressed bridge, its construction technology is gradually maturing. Its advantages of saving materials and high safety factor are also commonly used in bridge engineering. Next, the construction technology of the superstructure of cast-in-place continuous box girder of prestressed bridge is further introduced. 1. General situation of the project (taking Meihe Expressway K 1+ 136.393 overpass bridge as an example)? K 1+ 136.393 overpass bridge is a overpass bridge that spans Meizhou West Ring Expressway and Meihe Expressway. The design pile number of Meihe Expressway of this bridge is k1+013.93m ~ k1+259.393, and the length of the bridge is 246m, which is divided into two bridges. The whole bridge * * * is a triple, 1 ~ 3 is a joint, 20+2×25m is a joint, 4 ~ 7 is a joint, 4×25m is a joint, 8 ~ 10 is a joint, and 2×25+20m is a joint. The second steel beam is tensioned at two ends, the first and third steel beams are tensioned at one end, and the tensioning ends are respectively 0# and 10# abutment tops. The pile number of the intersection between West Ring Road and Expressway is k1+136.393 (xhk18+461.588), and the intersection angle is 90.26. The center of pier 5 coincides with the expressway in West Ring Road. Second, the superstructure construction technology foundation treatment, scaffold erection, formwork fabrication and installation, scaffold preloading, steel bar installation, concrete pouring, tensioning operation, hole grouting, anchor sealing, scaffold and formwork removal, etc. 1. Foundation treatment shall be carried out within the span and width of the bridge. Leveling and rolling for 4-5 times with a vibratory roller above 18T. The backfilling ground elevation is about 97.0m away from the box girder bottom elevation, the backfilling elevation of pier 0 #-4 # is 94m, that of pier 5 #-7 # is 95.5m, and that of pier 8 #- 10 # is 95m. The degree of compaction shall not be less than 90%, and a layer of stone chips with a thickness of about 10- 15cm shall be laid. According to the horizontal spacing of 1 ~ 1.2 m, the horizontal square timber of 20cm×5cm or 16# channel steel shall be arranged to disperse the pressure and ensure that the support is not deformed and stable during construction. After the foundation is backfilled, a certain number of drainage ditches shall be excavated to prevent rainwater from soaking the bottom of the support. 2. CKC standard portal scaffold (φ 42×1219×1930) is adopted for support erection and load-bearing installation. The bracket is light in weight and convenient to assemble, but its rigidity is small. In order to ensure the strength and overall stability of the stent, the stent is arranged in a four-body zigzag double-layer structure, and the bottom cushion of the stent is 20cm× 15cm. Portal frames are connected vertically and horizontally with φ48×3mm steel pipes between supports, steel pipes are used for internal and external support, and steel cables are used for symmetrical cable-stayed. The bracket density of box girder rib plate and diaphragm plate is 1 times, and the cantilever plate part can be reduced appropriately. The top frame of the upper support is laid with 10× 12 square meters, and its support height can be adjusted according to the terrain and the tripod of the portal frame, and the pre-camber can be adjusted through the upper support. After the scaffold erection is completed, accurately measure the position of the bearing center point on the pier with theodolite, and install the bearing according to the requirements of design drawings. 3. The camber of the bearing is set by the camber formula: f=f 1+f2, where f 1: the bearing is elastically deformed; F2: Pre-camber of beam deflection, the maximum value of which is set at the mid-span position of the beam and distributed in parabolic form. After calculating the pre-camber value of each point, adjust the bottom die through the adjustable screw jack or the base on the bracket. 4. After the formwork fabrication and installation and the bracket preloading bearing installation are qualified, the box girder bottom die shall be processed and installed according to the drawing size. The formwork is made of high-quality imported bamboo plywood (1.2cm thick), and the surface smoothness, smoothness and line fluency meet the aesthetic requirements, and the rigidity and strength meet the requirements.