Wulong River Bridge

Wulong River Bridge

Wulongjiang bridge, located at the downstream of wulongjiang River in Fuzhou City, Fujian Province, is a large-span prestressed concrete T-shaped steel frame bridge built earlier in China. It connects Qingliang mountain in North Xiabei village, Chengmen Town, Cangshan District, Fuzhou, and Jinniu Mountain in South Xianan village, Xiangqian Town, Minhou County. It is one of the important bridges of Fuzhou Xiamen highway. The length of the bridge is 552.22 meters, the width of the deck lane is 9 meters, the width of the sidewalks on both sides is 1.25 meters, the navigation clearance under the bridge is maintained at 12.3 meters according to the general high tide level (+ 5.00 meters), the elevation of the deck center is 19.45 meters, the whole bridge is flat slope, the bridge load is 26 cars and 100 trailers.

Brief introduction to the bridge

Wulongjiang bridge, located at the downstream of wulongjiang River in Fuzhou City, Fujian Province, is a large-span prestressed concrete T-shaped steel frame bridge built earlier in China.

Wulongjiang bridge is a T-shaped steel frame bridge, flying over the ancient crossing of wulongjiang River in the lower reaches of Minjiang River. It is one of the important bridges of Fuzhou Xiamen highway, with Qingliang mountain in the north of Xiabei village, Chengmen Town, Fuzhou suburb, and Jinniu Mountain in the south of Xianan village, Xiangqian Town, Minhou County. The river here is blocked by Qingliang mountain and Jinniu Mountain, forming a gorge. The river surface shrinks, the water depth is fast, and it is close to Haikou. The wind is strong, the waves are high, and the tide range is wide. It has always been regarded as a "natural moat".

Fu Xia highway has been open to traffic for decades, relying on ferry vehicles. In order to improve the traffic conditions of Fuzhou Xiamen highway, in early 1970, with the approval of the State Council, the Fujian Provincial Revolutionary Committee decided to build the wulongjiang bridge, which started on April 20 of that year and was completed and opened to traffic on September 26, 1971.

Design features

The length of wulongjiang bridge is 552.22 meters, the width of the deck lane is 9 meters, the width of the sidewalks on both sides is 1.25 meters, the navigation clearance under the bridge is maintained at 12.3 meters according to the general high tide level (+ 5.00 meters), the elevation of the center of the bridge deck is 19.45 meters, the whole bridge slope is flat, and the bridge load is - 26 cars and - 100 trailers. Both ends of the bridge have bridgeheads made of white granite. On both sides of the bridge, there are steel pipe railings decorated with diamond patterns, 13 steel pipe lamp posts in the air, and milky white street lamps.

The span is 58 + 3 × 144 + 58 (m), and each rigid frame is connected by 33m simply supported hanging beam. The bridge is 12m wide with 8M wide double box section and cantilever plates of 1.25m on both sides. The T-structure and abutment are connected by 6m long approach slab. The two t-structures in the middle adopt cantilever assembly, and the t-structures at both ends adopt cantilever casting construction. The substructure adopts reinforced concrete hollow pier, the maximum water depth is 26m, the tidal range is 5m, and there are two internal flow directions, the steel sheet pile cofferdam pipe column foundation is selected.

The bridge is a steel frame bridge with 4 piers and 5 spans, with a total length of 548m, a width of 9m for the carriageway on the deck and 1.25m for the sidewalks on both sides. The bridge is arched, the deck has no slope, the net height under the bridge is 12.3 meters, the elevation of the center of the bridge deck is 19.45 meters, the design load standard is steam-26, tow-100, and the crowd load is 200 kg / m2. There is a bridgehead made of white granite at each end of the bridge. On both sides of the bridge are diamond shaped steel pipe railings and lamp posts. The hydrogeology of the bridge site is extremely complex. The average water depth of the two piers in the river is 22 meters, and there is gravel overburden at the depth of 30 meters. The bedrock is crisscrossed and uneven.

This kind of bridge site is more complex than Wuhan Yangtze River Bridge, only next to Nanjing Yangtze River Bridge, but the bridge foundation of wulongjiang bridge has been successfully treated. Among the four piers, two piers on the riverside adopt shallow buried expanded foundation, and the two piers in the middle of the river are steel sheet pile cofferdam pipe column foundation. Under the condition that there are two positive and counter current directions every day and the tidal range is 5 meters, the bridge pier project is successfully completed due to the adoption of cage floating, positioning, pipe column sinking and steel sheet pile driving.

Put forward the reform

The widening and reconstruction plan of wulongjiang bridge has been basically finalized. As an important entrance and exit of Fuzhou South Gate, wulongjiang bridge will change the current supersaturated operation state. It is reported that the widening project will strive to start in the first half of next year. It is understood that at present, the reconstruction plan of wulongjiang bridge has been basically finalized. The preliminary plan is to build a new single bridge with two lanes and one-way traffic within 50 meters downstream of the original bridge. The bridge deck is 11.75 meters wide and forms a four lane use together with the old bridge. The old bridge is separated from the double track bridge, both of which are driven in one direction. The total length of the double track bridge and its connection is 1706.57 meters. The double track bridge is 548m long, and a single span bridge is designed according to two lane one-way traffic. The upper part adopts prestressed concrete continuous box girder, its strike is parallel to the old bridge, its appearance is consistent with the old bridge, and its lower part is pile foundation. The north bank has 826.57m connection length, and the double track is built along the old road. The south bank adopts 30m span approach bridge, 210m in length, to connect the line transition with the old road, and uses the plane intersection to connect with 324 National Road and provincial road 203 The south bank is 332m long.

With the continuous expansion of Fuzhou City, the demand for external traffic is also increasing, which mainly highlights the sharp increase of traffic volume at the entrance and exit, and the congestion of wulongjiang bridge and super large bridge at the south exit is more obvious. Although the connecting line of Fuzhou Xiamen Expressway undertakes the traffic diversion at the south exit, due to the charging factor, most of the vehicles (mainly trucks) entering and leaving Fuzhou at present The wulongjiang bridge is still in use, resulting in its supersaturated operation. Therefore, the relevant departments have decided to widen and reconstruct the wulongjiang bridge, so as to ease the traffic bottleneck at the south exit of Fuzhou City and speed up the expansion of the city to the East and the south.

Scheme implementation

Construction scale

The reconstruction and connection widening project of Wulong River Bridge starts from K16 + 325 of National Highway 324, crosses Wulong River and ends at K18 + 098 of National Highway 324, with a total length of about 1.774 km. Among them, the newly-built double track (K line + a line) is 1.774 km long (including 606 m of the newly-built double track bridge); the reconstructed line (K line + B line) is 1.764 km long (including 548.0 m of the reinforcement and reconstruction of the original wulongjiang bridge); the newly-built Xianan interchange ramp (C line) connecting with provincial road 203 is 433.4 m (including 160 m of the ramp bridge); and the newly-built pedestrian passage (D line) crossing the south side of the gorge is 154 M. Wulongjiang bridge and its cross-strait connection are constructed according to the standard of secondary highway with the function of urban class II trunk road; the design speed is 40 km / h; the C line of interchange ramp in the south of the gorge and the D line of pedestrian passage under the south of the gorge are designed at 30 km / h; the width of integral subgrade is 23 m (pavement width is 22 m), the width of each separated subgrade is 12 m (pavement width is 11 m), and the C line turns left ramp subgrade The width of the bridge is 10.25m (pavement width is 9.25m), and the base width of the D line of the underpass on the south side of the gorge is 3.5m (pavement width is 2.5m); the bridge deck adopts the high viscosity modified asphalt concrete pavement structure, and the connection pavement adopts the modified asphalt concrete pavement structure; the design vehicle load of the new bridge and culvert adopts highway class I, and the crowd load is 2.53kn/m2, and the traffic of the original wulongjiang bridge is restricted after inspection The design flood frequency is 1 / 50 for culvert and subgrade, and 1 / 100 for new double track bridge; the design maximum navigable water level is 6.699 m (luozero), the design minimum navigable water level is 0.5 m (luozero), the navigable net height is 8 m, the side height is not less than 5 m, the navigable net width is not less than 120 m, and the upper and bottom width is not less than 108 m; the basic intensity of the site is VII.

Route design

（1） Route layout

The layout of the bridge and its connecting route mainly includes: the widened K line, the branch lines a and B, the C line connecting the National Highway 324 and provincial highway 203, and the pedestrian passage D line crossing the south side of the gorge. （2） Horizontal and vertical technical indexes

The plane alignment design of this section comprehensively considers various factors and flexibly uses linear elements such as straight line, circular curve and transition curve to make the alignment balanced and smooth. In the design of vertical section, on the premise of using the old pavement and bridge, avoid high filling and deep excavation, control the filling height to the maximum, strive for the balance of filling and excavation, and reduce the engineering quantity.

The length of line k is 0.360km, the minimum radius of horizontal curve is 500m, and the maximum longitudinal slope is 3.93%; the length of line a is 1.414km, the minimum radius of horizontal curve is 70m, and the maximum longitudinal slope is 4.00%; the length of line B is 1.404km, the minimum radius of horizontal curve is 70m, and the maximum longitudinal slope is 4.00%; the length of line C is 0.433km, the minimum radius of horizontal curve is 55m, and the maximum longitudinal slope is 5.00%; the length of line D is 0.154km, the minimum radius of horizontal curve is 15m, and the maximum longitudinal slope is 4.397%. C. The ramp of line D shall be in accordance with the code for design of urban roads (cjj37-90), and warning signs shall be set according to the requirements of municipal roads. The rest shall be in accordance with the technical standard for Highway Engineering (JT gb01-2003).

Subgrade and pavement

（1） Subgrade design

The width of integral subgrade (K-line) is 23.00 m, and the layout of road width is 0.5 m (earth shoulder) + 2.5 m (sidewalk, non motor vehicle lane) + 0.5 m (guardrail) + 0.5 m (curb) + 4 × 3.75 m (motor vehicle lane) + 0.5 m (curb) + 0.5 m (guardrail) + 2.5 m (sidewalk, non motor vehicle lane) + 0.5 m (earth shoulder). The width of separated subgrade (lines a and b) is 12M, and the layout of road width is 0.5m (earth shoulder) + 2.5m (sidewalk, non motorized Lane) + 0.5m (guardrail) + 0.5m (curb) + 3.75m (motorized Lane)+

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