CCTV News: This morning (November 11), the main line of the Shenzhen-Zhongshan Corridor, the core transportation hub of the Guangdong-Hong Kong-Macao Greater Bay Area, a major national project, was officially opened. The Shenzhen-Zhongshan Corridor spans the east and west banks of the Pearl River Estuary, connecting Shenzhen, Guangzhou and Zhongshan, integrating "bridges, islands, tunnels and underwater interconnection", with a total length of about 28 kilometers, and is planned to be opened to traffic in June next year.

The Shenzhong Corridor is one of the most difficult cross-sea cluster projects in the world, adopting the construction scheme of "West Bridge and East Tunnel", the eastern part of the submarine tunnel is about 6.8 kilometers long, designed as a two-way eight-lane tunnel, and is the world's longest and widest submarine steel-shell concrete immersed tunnel. The undersea tunnel is connected to two artificial islands in the east and west, and the artificial island in the middle realizes the conversion between the undersea tunnel and the highways on the road, while the west artificial island undertakes the function of converting the tunnel to the sea bridge.

West artificial island: a new landmark on the Lingding Ocean of "Kunpeng on the Sea".

Driving in the 24-kilometer-long Shenzhong Tunnel, how can vehicles drive safely and smoothly from the bridge dozens of meters high on the sea surface into the undersea tunnel? The artificial island in the west of the Shenzhong Corridor solves this problem.

Viewed from the air, the West Artificial Island, which covers an area of about 13,7 square meters and is equivalent to 19 football fields, is like a Kunpeng spreading its wings on the surface of the Lingding Ocean.

The most important function of the West Artificial Island is to realize the conversion of bridges and tunnels, and the construction started in December 2016, which is the earliest project to start construction on the whole line. This "first son" of the entire Shenzhong Corridor on the Lingding Ocean plays a very key role in the overall stability and progress of the Shenzhen-Zhongshan Corridor. There is no substitute for the location and role, but where to start building such an artificial island in the vast sea?

Each of the 57 steel cylinders is 28 meters in diameter, 35-40 meters high, and weighs 650 tons. The construction team has developed the core technology of steel cylinder foundation pretreatment, which "grinds tofu" on the foundation of uneven and uneven construction sea area to reduce the strength of the hard soil layer, coupled with the self-developed 12-hammer linkage hammer group with the same frequency vibration, the giant steel cylinders were successfully driven into the seabed rock layer accurately and firmly, creating a world record of four and a half months of rapid island formation in the west artificial island.

In addition to the function of bridge and tunnel conversion, the west artificial island will also be used as an important place for the maintenance and management of tunnels and bridges, and this artificial island in the shape of "sea Kunpeng" will also become a new landmark on the Lingding Ocean.

East Artificial Island: Underwater interconnection

In order to realize the underwater interconnection function, the Shenzhen-Zhongshan Corridor is inseparable from the East Artificial Island. So how do you convert between islands and tunnels? How to connect with the adjacent road network on the ground to achieve multi-place interconnection? Follow the reporter to the East Artificial Island to continue to understand.

The east artificial island of the Shenzhen-Zhongshan Corridor is located on the south side of Shenzhen Bao'an Airport, and is connected to the submarine immersed tunnel in the west, which is the gateway project of the Shenzhen end of the Shenzhen-Zhongshan Corridor.

Viewed from the air, the T-shaped main line tunnel of the East Artificial Island and the ramp tunnel bridges on both sides are like a seabird soaring over the sea with its wings. Before construction began in 2017, it was still a shallow beach. The island is filled with sea sand with an area of nearly 35,48 square meters, which is equivalent to <> standard football fields.

CCTV reporter Li Weidai: This is a diversion point of the underwater interconnection hub of the eastern artificial island of the Shenzhen-Zhongshan Channel, we are now 15 meters below the sea surface, and in front of me is the submarine immersed tube tunnel of the Shenzhen-Zhongshan Channel, which is divided into two forks, and the vehicles from Zhongshan to Shenzhen in the future will be smoothly connected to the ground road network through this "Y" shaped fork road diversion.

There are four such tunnel ramp points and merging points on the East Artificial Island, and they work together with the main line tunnel on the island to realize the diversion and merging of vehicles.

The underwater interchange is in a relatively closed environment, which has a certain impact on the driving sight distance. As early as the preliminary study of the project, the professional team simulated driving in various states through a professional software system, optimized the design of the continuous partition wall at the confluence of the main line tunnel and the ramp tunnel as a column to increase permeability, and adopted intelligent electronic safety assistance facilities to improve the safety of driving.

Reporter's visit: immersed tube floating installation integrated ship

The undersea tunnel section of the Shenzhong Passage is about 6.8 kilometers long, with eight lanes in both directions, and the immersed pipe section of the tunnel is connected by 32 pipe sections and a final joint, each of which is 165 meters long, 46 meters wide and 10.6 meters high, and weighs about 8,<> tons. How can these "Big Macs" be floated in place and installed accurately on the vast sea? It all depends on a core equipment, which is the world's first immersed tube floating installation integrated ship independently developed by China.

With a length of 190.4 meters, a beam of 75 meters, a depth of 14.7 meters, and a deck area equivalent to two football fields, this immersed tube floating installation integrated ship tailored for the Shenzhong Channel is the world's most powerful installation capacity, the highest sinking accuracy, the most efficient construction operation and the most advanced performance of the special ship for immersed tube construction of submarine tunnels. From above, it resembles a huge rectangular steel clamp that holds the immersed tube firmly in the center of the ship.

The biggest highlight of the floating installation integrated ship is that it is equipped with an automatic driving system, which perfectly solves all kinds of difficulties in the undocking and floating transportation of immersed tubes. All immersed pipes in the Shenzhong Channel need to be undocked from the immersed tube prefabrication plant on Guishan Island, floated to the immersed tube installation area near the West Artificial Island, floating nearly 50 kilometers, after 7 channel conversions, the width of the channel is only 200 meters, and passing through the most busiest Lingdingyang channel in China, the whole process will face many safety risks.

Compared with the traditional floating installation method of pipe sections, the integrated ship greatly reduces the dredging amount of the floating channel, which is more environmentally friendly and economical. Through the intelligent driving system, after the immersed tube floats to the designated sea area, the installation system on the integrated ship will show its skills.

Through the display screen, the commander accurately grasps the specific position of the immersed tube on the seabed; At the same time, the dynamic signal acquisition information system is used to monitor the attitude of the immersed tube in real time. With the close cooperation of multiple systems, the immersed tube is lowered to the foundation bed to achieve preliminary docking. Then, with the help of the pressure of seawater, hydraulic crimping is carried out, so that the immersed tube docking can achieve a tight fit, and the drip does not leak. At present, the docking accuracy of all pipe sections has been realized in the submarine immersed tunnel of the Shenzhong Passage within five centimeters, and seven consecutive pipe sections have achieved millimeter-level accuracy.

"Beidou" helps the seabed to thread the needle and seamlessly connect 80,000 tons of immersed tubes

The immersed pipe section of the undersea tunnel of the Shenzhong Passage is composed of 32 pipe sections weighing about 8,<> tons and a final joint. How do you ensure that these tubes are installed precisely and accurately on the seabed the first time? The Beidou navigation system has contributed a lot.

This is the world's first extra-long, ultra-wide, two-way eight-lane steel-shell concrete immersed tunnel. The 6.8-kilometre-long section is divided into 32 sections and final joints, installed in steps, and weighs 8,<> tonnes per immersed tube.

First of all, the giant immersed tube must be transported with a cable, accurately placed in the foundation groove of the seabed, and then docked with the front pipe section in a tight end-to-end manner, and it must be safely used for 100 years.

Under invisible water, the installation error of 5 cm can be said to be "threaded needle embroidery" for an immersed tube that is more than 160 meters long, 46 meters wide and 10 meters high. If the positioning is inaccurate or the accuracy is insufficient, resulting in too large deviation in the installation of the pipe section, the project must be suspended and "fine-tuned".

When the project was launched, it coincided with the commissioning of the Beidou system. In order to introduce the power of Beidou, the team repeatedly did thousands of tests and verifications on land, at sea, and on the immersed tube, and finally formed a plan, which was carried out by the Beidou satellite antenna on the ship and the nearby reference reference station to carry out differential positioning of the immersed tube, with an accuracy of up to millimeters.

After entering the water, the position and attitude of the immersed tunnel under the water are clearly displayed on the screen. The positioning performance of Beidou is stable and reliable, which makes the project progress high-quality and efficient.