Nan'ao Bridge

Nan'ao Bridge

Nan'ao bridge is a cross sea passage connecting Chenghai District and Nan'ao County in Shantou City, Guangdong Province, China. It is located above Houjiang Bay and is a part of northeast passage of Shantou City.

The construction of Nan'ao bridge started on January 20, 2009;

The closure project of the whole line was completed on July 24, 2014;

It was put into operation on January 1, 2015.

Nan'ao bridge starts from laiwuwei, Chenghai District, Shantou City in the west, crosses houjiangwan Strait in the East and ends at the entrance of Nan'ao Island Ring Expressway in the East. The total length of the line is 11.08 km, and the length of the whole bridge is 9.342 km. The bridge deck is a two-way two lane second-class highway with a design speed of 80 km / h.

Construction process

On February 13, 1995, the main project of Nan'ao bridge was started. Due to the lack of follow-up funds at that time, the project was forced to stop.

On January 25, 2006, the development and Reform Commission of Guangdong Province approved the construction of Nan'ao bridge project. At the same time, the government of Guangdong Province also approved that Nan'ao bridge is a non operating charging project and included in Shantou's annual ticket loan repayment project.

On February 6, 2007, the design concept report meeting of Nan'ao bridge was held in the conference hall of Shantou Municipal government.

On March 35, 2008, the preliminary design scheme of Nan'ao bridge was approved by the Department of transportation of Guangdong Province.

On January 20, 2009, the construction of Nan'ao bridge started.

On October 7, 2013, the main tower capping project of Nan'ao bridge was completed.

On May 4, 2014, Nan'ao bridge completed the East and West pylons of the main bridge;

On July 6, the closure of the main bridge and the East approach bridge of Nan'ao bridge was carried out;

On July 14, Nan'ao bridge completed the West span closure of the main bridge;

On July 25, the middle span closure project of Nan'ao bridge was carried out;

On July 27, the closure project of Nan'ao bridge was completed;

On December 13, Nan'ao bridge was completed and accepted;

On the 30th, the LED lights of Nan'ao bridge were on for trial.

On January 1, 2015, Nan'ao bridge was put into trial operation.

Bridge location

Nan'ao bridge is located in Shantou City, Guangdong Province, China. It starts from Laiwu tourist resort, Chenghai District, Shantou City, Guangdong Province in the west, crosses houjiangwan Strait, passes Fengyu Island, ends at changshanwei of Nan'ao Island in the East, and connects with Nan'ao ring road by pingjiaokou. It is one of the important passageways in the northeast of Shantou City and an important bridge connecting Shantou City and Nan'ao County.

Architectural design

building structure

Overall layout

Nan'ao bridge is composed of main bridge on water, east-west approach bridge, east-west approach road, two pylons, piers and their ramps. The section from laiwuwei to Fengyu island is arranged from southwest to northeast, and the section from Fengyu island to Nan'ao is arranged from northwest to Southeast.

 

Design concept

The low pylon cable-stayed bridge is a semi flexible bridge between beam bridge and cable-stayed bridge, so it has the common advantages of both beam bridge and cable-stayed bridge. In the preliminary design, the low pylon cable-stayed bridge is adopted after comprehensive comparison and selection of design and construction technical difficulty, channel adaptability, wind resistance and seismic performance, structural durability, later maintenance workload, landscape effect, etc.

 

Design features

Design parameters

The total length of Nan'ao bridge is 11.08 km, and the total length of bridge part is 9.342 km. Among them, the length of West approach bridge is 7.093 km, the length of East approach bridge is 1.758 km, the net width of bridge deck is 11 m, the structural width of approach bridge is 12 m, and the structural width of main bridge is 14.4 M. The top width of the main beam is 14.4m, the cantilever on both sides is 1.1m, the cantilever end is 60cm thick and the root is 100cm thick; the inclination of the web is 1:3.275, the width of the beam bottom is 8m to 10.443m, the height of the box beam fulcrum is 8m, and the height of the mid span beam is 4m. The thickness of the top plate of the box girder is 28 cm, the thickness of the bottom plate is 30-80 cm, and the thickness of the web plate near the fulcrum is 30-80 cm The thickness of the top plate of Block 0 is 80cm, the thickness of the bottom plate is 120cm, two 1m thick diaphragms are set; the thickness of the side fulcrum diaphragms is 2m, the total height of the main tower is 69.415m, the height of the upper tower column is 30m, 5m along the bridge, 2m across the bridge, and the clear distance between the two tower columns is 11.4m; the height of the lower tower column is 31.415m, and the clear distance between the two tower columns is 8.4m The direction of the bridge is 5 meters, and the transverse direction of the bridge changes from 3.5 meters to 5 meters, with a wall thickness of 80 cm. There are 48 stay cables in the whole bridge, the distance between the cables on the beam is 5m, and the distance between the cables on the tower is 1m.

 

 

Equipment and facilities

Lighting facilities

As of December 30, 2014, all 3078 LED lights of Nan'ao bridge have been installed. 2338 LED lights have been installed in the approach bridge and main bridge of the bridge. There is no traditional light pole, and the light source directly shines on the asphalt road. 600 LED lights are installed on the outside of the barrier. 140 LED lights are installed on the outside of the main bridge barrier, with LED projection lights and led floodlights.

 

Toll facilities

On March 19, 2015, the people's Government of Guangdong Province agreed that after the Nan'ao bridge project was completed and opened to traffic, a toll station of Nan'ao bridge should be set up at the place where the bridge connects to Nan'ao Island. Vehicles can enter Nan'ao Island only after paying at the toll station.

 

Operation

Fare system

On March 19, 2015, the people's Government of Guangdong Province made an official reply on issues related to vehicle tolls of Nan'ao bridge in Shantou City

It is agreed that after the Nan'ao bridge project is completed and opened to traffic, Nan'ao bridge toll station will be set at the place where the bridge connects to Nan'ao Island to collect one-way two-way toll for vehicles entering the island. The toll models are classified according to the physical parameters such as the number of axles (wheels) and the height of the front of the vehicle. The toll coefficients of the first to the fifth categories of vehicles are 1, 1.5, 2, 3 and 3.5 respectively; the one-way toll standards are 48, 72, 96, 144 and 168 yuan / vehicle respectively.

 

Traffic matters

As of May 2015, pedestrians and the following vehicles are not allowed on Nan'ao bridge: non motor vehicles, motorcycles, tractors, special vehicles for the disabled, tracked vehicles, special wheeled mechanical vehicles, articulated buses and full trailer. In case of special weather (such as typhoon, tropical storm, fog, etc.), Nan'ao bridge will be subject to traffic control or bridge closure according to the situation; buses (or vehicles of the same level) are not allowed to get on the bridge in strong wind of level 9; bridges will be closed in strong wind of level 10 (including level 10).

 

traffic flow

During the Spring Festival in 2017, the traffic flow of Nan'ao bridge into the island exceeded 60000, and the traffic flow out of the island was about 57000.

 

Construction achievements

Technical problems

construction technique

Aiming at the complex construction conditions, Nan'ao bridge adopts technical means to overcome them

1. Dongxi estuary of Hanjiang River and Fengyu island are respectively located in the North East and west sides of the bridge site, and the flow direction of the sea current is complex due to the influence of air. Through the analysis of the flow direction, the route is reasonably arranged, and the influence of artificial structures on the flow direction is minimized, so as to reduce the sprint of the water flow on the bridge foundation.

2. The global positioning system (GPS) technology is used to establish the mobile phone control network, and the encrypted control network is established through the construction of limited pier to solve the problem of cross sea survey.

3. Combined with many experiences, the geological problems can be solved; driven steel pipe pile foundation is adopted in deep water area to avoid the high risk of bored pile construction of offshore deep-water platform; multiple inclined piles are stressed together to make the bridge foundation more reliable; bored pile foundation is adopted in shallow water area, most of the bearing capacity of super long friction pile is used to bear its own weight, and the soil at pile end is strengthened by grouting at pile bottom to effectively improve the stability High bearing capacity of single pile.

4. The systematic seismic design scheme solves the problems of high seismic intensity and poor geological conditions in the bridge site by changing the structural stiffness and system damping.

 

Construction problems

During the construction of Nan'ao bridge, the following problems are encountered:

1. Nanao county has a small population and limited financial resources, so the most economical and reasonable project scheme should be selected under the condition of ensuring the quality and construction period.

2. The scale of the project is large, and the approach bridge accounts for 95% of the total length of the bridge.

3. The construction conditions of the project are complex, with large waves, frequent typhoons, weak and uneven strata, and large earthquake intensity. Due to the small scale of the upper part of the bridge, the selection of foundation scheme has a great impact on the construction scale of the whole bridge under specific construction conditions.

4. The project is in the marine environment with serious corrosion. Reasonable anti-corrosion measures are the key to ensure the service life of the bridge.

 

Cultural characteristics

Directional album

Chinese PinYin : Nan Ao Da Qiao