Introduction of Nanjing Yangtze River Tunnel?

Nanjing Yangtze River Tunnel is located between Nanjing Yangtze River Tunnel and Nanjing Yangtze River Third Bridge. It is one of the important river-crossing passages connecting Nanjing Jiangbei New District, Hexi New City and Jiangnan main city, which is of great significance for alleviating the traffic pressure of Nanjing river-crossing and promoting the development along the river. The Yangtze River Tunnel is a two-way six-lane tunnel with a speed of 80 kilometers per hour. The total investment of the project is about 3.3 billion yuan, and the total length of the left and right shield tunnels crossing the Yangtze River is 6042 meters.

Before the 20 15 Nanjing Yangtze River Tunnel was completed, Nanjing Yangtze River Tunnel was the project with the most complicated geological conditions, the most technical problems and the greatest construction risk among the super-large shield tunnels built and under construction in the Yangtze River valley of China, and was called "the first Yangtze River Tunnel".

Nanjing Yangtze River Tunnel, with a diameter of 14.93m, is the second shield tunnel in the world. Nanjing Yangtze River Tunnel Engineering Company has carried out nearly 60 scientific research projects and tackled key scientific and technological problems, and applied for patents 15. Among them, the prototype test of super-large segment lining structure was included in the national "863" plan demonstration project, which filled the gaps in related fields of underground engineering construction.

At the end of 20 13, Nanjing Yangtze River Tunnel won the Luban Award, the highest honor for engineering quality in the national construction industry, and became the first river-crossing tunnel project in China to win the Luban Award. 20151February, won the national quality engineering award.

Building scale

Nanjing Yangtze River Tunnel is located in Huangjia Village, Pukou District, starting from the access point of the interchange transition section between Binjiang Expressway in the south of the Yangtze River and Yingtian Street West Extension Line, and ending 500 meters from Jiangbei Toll Plaza to the expressway. The whole tunnel is 5853 meters long, and it is built according to the scale of six-lane urban expressway, with a design speed of 80 km/h.

Nanjing Yangtze River Tunnel Project is one of the most difficult and challenging projects with the longest tunnel length, the largest shield diameter in China. It is located between Nanjing Yangtze River Bridge and Nanjing Yangtze River Third Bridge, connecting Jiang Xinzhou-Pukou District, a new Hexi urban area.

China Railway Construction is an investor in the Nanjing Yangtze River Tunnel Project, with a capital contribution ratio of 80%, Nanjing Communications Construction Investment Holding (Group) Co., Ltd. 65,438+00%, and Nanjing Pukou State-owned Assets Management (Holding) Co., Ltd. 65,438+005,438+055,438+04 million yuan. The operating period of the company is tentatively set at 34 years, including 4 years for construction and 30 years for operation and management.

The left shield tunnel was built by China Railway 14th Bureau, and the right Jiajiang Bridge in Jiang Xinzhou was built by China Railway 15th Bureau.

Jiajiang Bridge in Jiang Xinzhou, Nanjing is a part of Nanjing Yangtze River Tunnel, connecting jianye district Yangtze River Avenue and Jiang Xinzhou, with a total length of 665.5 meters and a main span of 248 meters. It is a self-anchored suspension bridge, which is the first one in China. The bridge is two-way and six-lane, with sidewalks for pedestrians and non-motor vehicles. This bridge crosses Jiajiang in Jiang Xinzhou and lands in Jiang Xinzhou. There is a special interchange for pedestrians, bicycles and cars to drive on Jiangxinzhou or directly cross the Yangtze River. From Jiajiang Bridge in Jiangxinzhou to Jiang Xinzhou, driving a few hundred meters further, it officially entered the main body of Nanjing Yangtze River Tunnel.

The Nanjing Yangtze River Tunnel Project starts from the access point of the transition section of the Jiangnan Binjiang Expressway and Yingtian Street Interchange, and ends at the 500-meter junction of Jiangbei Toll Plaza and Expressway. The total length of the whole project passage is about 6.2 kilometers. The design speed is 80 kilometers per hour, and the scheme of "left branch shield tunnel+right branch bridge" is adopted. The construction length of the left branch shield tunnel is 3.9 kilometers. With a diameter of nearly15m, the shield is one of the largest shield tunnels in the world, second only to the shield machine of Shanghai Yangtze River Tunnel.

Youcha Jiang Xinzhou Bridge is a self-anchored suspension bridge with a total length of 665.5 meters and a main span of 248 meters. Its main tower is107m high. The bridge has two lanes and six lanes, and there is a special sidewalk for pedestrians to cross the river on foot. Nanjing Yangtze River Tunnel adopts "Big Mac" shield machine, with cutter head diameter of14.93m, weight of about 4,000 tons, length of130m and height of 5 floors.

technical characteristics

Compared with other tunnels, tunnels are extremely safe.

In case of an accident, the public can go to the passage under the tunnel surface through the escape slide. Every 80 meters, there is a big cover on one side of the tunnel. As long as the citizens press the switch, the cover will pop open, and then the citizens can follow the escape slide to the passage under the road. This design is mainly used to escape when there is a fire in the tunnel and a lot of smoke is generated. In addition, there will be 23 kinds of settings in the tunnel, such as sprinkler heads, intensified lighting, lane lights, horns, surveillance cameras, anti-collision side stones, roadside ditches, cable passages and safety passages, which can fully guarantee driving safety.

Known as the "first difficulty in underwater construction" in China, the left tunnel of Nanjing Yangtze River Tunnel rushed out of the Jiang Xinzhou mouth, which means that the Yangtze River Tunnel with a length of more than 3,000 meters was officially connected. The excavation diameter of this tunnel is nearly 15m, and it is the largest shield tunnel in the world.

Jiang Xinzhou is adopted in the Nanjing Yangtze River Tunnel, and the tunnels excavated from north to south should leave holes on this small island, thus reducing the length of the whole tunnel under water.

Nanjing Yangtze River Tunnel will cross the Yangtze River at a depth of 65 meters, and the water pressure per square centimeter of the tunnel is as high as 6.5 kilograms. It is a world-class river-crossing tunnel project with the greatest technical difficulty, the most complicated geological conditions and the most problems and challenges in the Yangtze River Basin. The risk of roof caving, river bottom settlement and permeable collapse in the construction process is huge and unprecedented. The completion of the left line marks the successful solution of the world-class technical problems faced by the Nanjing Yangtze River Tunnel Project, and also marks a major breakthrough in the river-crossing tunnel technology in China under special unfavorable hydrogeological conditions.

According to reports, the construction of Nanjing Yangtze River Tunnel adopts two of the world's most advanced slurry balance shield machines, and the excavation diameter is equivalent to five stories high, making it the largest shield tunnel in the world.

There are more than 60 bridges on the Yangtze River under construction in China, but only Wuhan in the middle reaches has been built, and only Nanjing and Chongming Island in the Yangtze River estuary are under construction.

Nanjing Yangtze River Tunnel Project is facing many world-class technical problems and challenges, which can be summarized into six aspects.

First, it is "big". The shield used in Nanjing Yangtze River Tunnel has a very large diameter, and the excavation diameter reaches 14.96m, making it one of the largest slurry balance shield machines in the world. With the increase of shield machine size, the construction difficulty and risk increase geometrically.

Second, it is "high", and the water and soil pressure reaches 6.5kg/cm2 (equivalent to 65m head pressure) during construction, ranking first in the current super-large diameter shield underwater tunnel project;

Third, it is "deep". From the deepest part of the tunnel to the bottom of the river 60 meters, the stratum is extremely permeable, and all the head pressure directly acts on the tunnel, so the risk of river bottom excavation is huge;

Fourth, it is "thin". The thickness of the river bottom shield is ultra-shallow. In the scouring section with the length of 150m in the middle of the river, the thickness of the overburden above the tunnel is less than 1 times of the tunnel diameter (about 10.79m, which is only 0.72 times of the excavation diameter), and the geology is fine sand layer, so the risk of collapse and roof fall during construction is great. The shield machine originates and receives ultra-shallow burial, and the thickness of covering soil above the tunnel entrance section is only 5.5m (about 0.37 times of the excavation diameter), which is the shallowest burial depth in similar tunnels. Therefore, the technical requirements for the stability of excavation surface and the control of ground settlement during shield excavation are extremely high.

Fifth, it is "long". Due to the long underwater excavation distance and complex geological conditions, it is extremely difficult to change the tool during excavation. Two two-way six-lane 3020m shield tunnels need to be excavated once, which requires extremely high cutter protection. Three kilometers of Nanjing Yangtze River Tunnel is equivalent to subway shield tunneling 17 kilometers, and the abrasion of tools crossing the gravel layer with high content in time is equivalent to 30 kilometers of similar shield tunneling in soft soil.

The sixth is "risk". In terms of design, the design theory and experience of super-large diameter underwater shield tunnel are almost blank in China, and the experience abroad is also insufficient. In terms of construction, the geological conditions are extremely complicated. The tunnel passes through silt, silt, gravel sand, pebbles and weathered rocks at the bottom of the river. The permeability coefficient is more than 1000 times that of clay layer, which is loose and easy to collapse. All the indexes of high water permeability and high water pressure have reached or exceeded the risk prevention limit of similar projects in the world.

work progress

On the morning of August 22, 2009, with the huge rotating cutter head of the shield machine on the right line of Nanjing Yangtze River Tunnel breaking through the last layer of reinforcement area, the Nanjing Yangtze River Tunnel Project, which was built by China Railway Construction 14th Bureau Group, ushered in the full-line penetration of the tunnel, following the smooth exit of the left line tunnel on May 20, which indicated that the river-crossing tunnel in China Yangtze River Basin had successfully overcome all the difficulties in construction. All risks have been avoided, and a major breakthrough has been made in the construction under special unfavorable geological conditions, which also marks that the construction technology level of super-large diameter shield tunnel in China has reached a new height.

According to Qian Qihu, an authoritative expert, former vice-chairman of the International Society of Rock Mechanics, academician of China Academy of Engineering and director of the Nanjing Yangtze River Tunnel Expert Committee, Nanjing Yangtze River Tunnel is a project with the most complicated geological conditions, the most technical problems and the greatest construction risks among the super-large shield tunnels built and under construction in the Yangtze River valley of China, and it is truly the "First Yangtze River Tunnel".

Since the foundation stone was laid in March 2005 and the project started in September, the project construction unit Nanjing Yangtze River Tunnel Co., Ltd., the construction unit China Railway Construction 14th Bureau Group and the design unit China Railway Construction Fourth Survey and Design Institute have bravely met the challenge, pushed the project to overcome difficulties with scientific research strength and advanced management, and constantly overcome world-class technical problems. Nanjing Yangtze River Tunnel Company and China Railway Construction 14th Bureau Group resolutely implement the construction policy of "stability first, safety first, foolproof, and ensuring success", and organize teams of experts and research institutes to tackle key problems, solve technical problems, and promote scientific and technological innovation. The project invested more than 30 million yuan in scientific research, completed more than 30 special demonstrations, applied for patents 15, carried out scientific research on 29 sub-topics of 5 major topics, and achieved many scientific research achievements, filling the gaps in related fields, among which the prototype test of super-large segment lining structure was included in the national "863" plan demonstration project.

The left and right tunnels of Nanjing Yangtze River Tunnel are connected safely and smoothly. The tunnel formed is smooth, tidy, beautiful, impermeable and leakproof, and the segment assembly is error-free. The technology and quality of segment production and tunnel construction have reached the world-class level, which has been unanimously recognized and highly praised by experts and insiders at home and abroad.

The left line of Nanjing Yangtze River Tunnel Project was completed on May 20th, 2009 10, and the right line was completed on the morning of August 22nd, 2009.

Construction significance

After the completion of Nanjing Yangtze River Tunnel, its traffic capacity is twice that of Nanjing Yangtze River Bridge, which will change the only bridge across the Yangtze River in Nanjing and greatly ease the traffic pressure. Tunnel construction is conducive to optimizing urban spatial structure, improving urban radiation function, promoting cross-strait integration and interaction, making full use of underground space, protecting Nanjing's unique cultural landscape and ecological environment, shortening the distance between Jiangnan and Jiangbei, and promoting the rapid economic development of Jiangbei.

With the construction of Nanjing cross-river tunnel, Pukou District in the north of the Yangtze River and Jiang Xinzhou Island in the south of the Yangtze River will be the biggest beneficiaries.

Its construction will change the current single-bridge traffic mode across the Yangtze River, which is of great significance to alleviating the traffic pressure across the Yangtze River in Nanjing and promoting the development along the Yangtze River.

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