The third phase of Nanping line passes through Maluan Mountain Park, and the bridge site has high requirements for ecological environmental protection. Objective conditions require that the structure design must have :(1) minimize the frequency and cost of bridge maintenance; (2) Fast construction progress. Maluan overpass main line bridge adopts integral abutment bridge. Design load of Maluan Mountain Overpass main line bridge: Cheng-A class; Peak acceleration coefficient of ground motion: 0.1g(seismic intensity ⅶ). The bridge is divided into left and right Bridges, which are 28.96m+30m+28.96m=87.92m continuous structure box girder.
The cross-sectional arrangement of the bridge is: 0.5m (railings) + 16M (carriageway) +0.5m (access road and railings) =17m. Unidirectional transverse slope 2%. The full width of each box girder is 17m, the bottom width of the single box chamber is 3.95m, the outer overhang of the box girder is 2.25m, the end of the overhang is 20cm thick, the root is 40cm thick, the standard thickness of the box girder top plate is 25cm, and the top plate is thickened to 45cm within 1.2m near the beam. Two 180×120cm rectangular piers are used for the piers and piers, which are consolidated with the main beam. A drilling (punching) hole grouting pile of φ180 is connected under the pier column, and a tie beam is set on the top of the pile foundation. The bridge adopts the method of pier and beam consolidation, which cancels the expansion joints, deck expansion devices and supports at the pier. The integral abutment eliminates expansion joints, deck expansion devices and supports. The abutment and the superstructure are consolidated into a whole, the thickness of the abutment is 1m, and there are 4 bored piles with a diameter of 150 under the abutment. The abutment guide plate adopts Z-shaped guide plate (invention patent of Fuzhou University). Z-shaped guide plate structure, including upper plate (horizontal length 5.055m, thickness 35cm), inclined plate (horizontal length 1.074m, thickness 21cm) and lower plate (horizontal length 1.871m, thickness 35cm) connected successively from top to bottom. The Angle between the inclined plate and the horizontal line is 45º.
The bridge was originally designed as a slotted bridge. Comparing the material consumption and cost of the integral bridge and the jointed bridge, it is found that the number of pile foundation of the integral bridge abutment and pier decreases, the size of the cap decreases, and the cost decreases obviously. Abutment reinforcement increases, and the cost rises slightly. Overall, the overall construction cost of the bridge is 13% (about 300,000 yuan) less than that of the original design of the slotted bridge. After completion, it will greatly reduce the late maintenance and maintenance costs, avoid the maintenance and replacement of expansion joints, bearings caused by traffic congestion or even interrupted, improve the safety of the bridge and driving, the social and economic benefits of the full life of the bridge is very obvious.
The main bridge of Maluan Mountain Overpass is built by Shenzhen Transportation and Public Facilities Construction Center, designed by Shenzhen Municipal Design and Research Institute Co., LTD., constructed by Hangzhou Xiaohong Construction Group Co., LTD., and supervised by Shenzhen Zhaoye Engineering Consulting Co., LTD. The College of Civil Engineering of Fuzhou University is responsible for the scientific research project based on the bridge. The design of the bridge has been guided and the structure of the bridge has been studied. The bridge was completed and opened to traffic in May 2018.
（a）Side view of bridge
（b）Bridge deck photos