The construction of Dalian Bay subsea tunnel started on March 30, 2017[2]；The whole line will be completed on September 29, 2022[3]；Open to traffic on May 1, 2023[1]。
Dalian Bay Submarine Tunnel starts from the southDalian Donggang Business DistrictRenmin Road runs through the sea area of Dalian Bay and north to No. 20 Road of Barracuda Bay in Dalian Barracuda Bay area;The total length of the tunnel is 5.1 kilometers, including 3 kilometers of subsea immersed tunnel section, 1.8 kilometers of land section, and 0.3 kilometers of link road section;The road is designed as a two-way six lane urban expressway with a design speed of 60 km/h[4][44]。
Construction of Dalian Bay subsea tunnel commenced
On March 30, 2017, the construction of Dalian Bay subsea tunnel started[2]；On May 24, Dalian Bay subsea tunnel project was selectedNational Development and Reform Commission of the People's Republic of ChinaTypical cases of the second batch of PPP projects;On August 1, the construction of the dry dock project of the Dalian Bay subsea tunnel was started, marking that the Dalian Bay subsea tunnel has entered the stage of substantial construction[7]。
On May 1, 2019, the foundation trench excavation project of Dalian Bay subsea tunnel was commenced[32]；On September 24, the foundation bed riprap process was started for the north bank project of Dalian Bay subsea tunnel[8]；On December 6, the last concrete pouring at the dock mouth and the middle bulkhead of the caisson dry dock prefabrication yard of the Dalian Bay subsea tunnel was completed[9]。
Prefabrication of immersed tube in dalian bay subsea tunnel
On April 25, 2020, the pouring of E5S6 immersed tube section of Dalian Bay subsea tunnel began, marking that Dalian Bay subsea tunnel entered the main construction stage[10]；On October 17, the caisson prefabrication west dock of Dalian Bay subsea tunnel began to fill water[11]；On October 23, the water filling operation of the west dock of the immersed tube prefabrication of the Dalian Bay subsea tunnel was completed, marking the completion of the first batch of immersed tube prefabrication and outfitting operations of the west dock of the Dalian Bay subsea tunnel[12]；In November, the first three immersed tubes of Dalian Bay subsea tunnel were undocked[13]；On December 9, the installation of the first immersed tube of the Dalian Bay subsea tunnel was completed[14]。
E5 pipe joint of Dalian Bay subsea tunnel
On March 9, 2021, the first standard pipe joint of Dalian Bay subsea tunnel - E2 pipe joint and E1 pipe joint will be connected[15]；On May 20, the connection between E4 and E3 pipe joints of Dalian Bay subsea tunnel was completed[16]；On June 8, the deepest pipe joint E5 of Dalian Bay subsea tunnel was installed[17]；On June 19, the pouring of E7S1 segment of Dalian Bay subsea tunnel was completed, and the second batch of pipe segments in the west dock were prefabricated[18]；In July, the installation of E6 pipe joint of Dalian Bay subsea tunnel was completed[19]；On September 15, the butt joint of E9 pipe joint of Dalian Bay subsea tunnel was completed[20]；On November 11, the docking of E11 pipe joint and E10 pipe joint of Dalian Bay subsea tunnel was completed, marking the launching of the launching test of the docking structure between the offshore immersed pipe section and the onshore cast-in-place section of Dalian Bay subsea tunnel[21]；On November 27, the connection between E12 pipe joint and E11 pipe joint of Dalian Bay subsea tunnel construction project was completed[22]。
Site of Dalian Bay subsea tunnel
On January 11, 2022, the water injection construction of the south bank basin of the Dalian Bay subsea tunnel was started[23]；On March 6, the installation of E13 pipe joint of Dalian Bay subsea tunnel was completed[24]；On March 28, the installation of E14 pipe joint of Dalian Bay subsea tunnel was completed[25]；On April 6, the concrete pouring of the first section of the floor of the land area project on the south bank of the Dalian Bay subsea tunnel was completed in 2022, marking that the land area project on the south bank of the subsea tunnel has entered the stage of full speed construction of the main body;On the same day, the construction of 4775 retaining water stop piles for the land area project on the south bank of the Dalian Bay subsea tunnel was completed, marking the completion of water stop for all the foundation pits of the land area project[26]；On April 29, all immersed tube prefabrication and one time outfitting of Dalian Bay subsea tunnel were completed[27]；On May 11, the installation of full curve pipe joint E15 of Dalian Bay subsea tunnel was completed[28]；On May 18, water injection started in the buried section on the north bank of the Dalian Bay subsea tunnel[29]；On June 3, the installation of E16 pipe joint of Dalian Bay subsea tunnel was completed[30]；On July 5, the installation of E17 pipe joint of Dalian Bay subsea tunnel was completed[31]；On July 22, the excavation of the main line foundation trench of the Dalian Bay subsea tunnel project was completed and accepted[32]；On August 5, the installation of the last immersed tube of the Dalian Bay subsea tunnel was completed, marking the completion of the installation of the immersed tube of the Dalian Bay subsea tunnel[33]；On August 12, the foundation pit excavation of the whole line of the Dalian Bay subsea tunnel land project was completed[34]；On September 9, the final joint of Dalian Bay subsea tunnel was installed and accurately docked with E18 pipe joint[35]；On September 29, the Dalian Bay subsea tunnel was fully opened[3]；In November, the construction of the high exhaust tower on the south bank of the Dalian Bay subsea tunnel project began[36]。
Opening Ceremony of Dalian Bay Submarine Tunnel
On January 1, 2023, the capping concrete pouring construction of the high exhaust tower on the south bank of the Dalian Bay subsea tunnel project will be completed, and the decoration and electromechanical installation will be fully started[36]；On January 28, the Dalian Bay subsea tunnel project began to resume in an orderly manner[37]；In March, all jet fans of the whole line of Dalian Bay subsea tunnel were commissioned and successfully commissioned[38]；On April 10, the underpass of Renmin East Road on the south bank of Dalian Bay subsea tunnel was put into operation, marking the opening of the whole line of Renmin East Road of Dalian Bay subsea tunnel[39]；On April 12, Dalian Bay Subsea Tunnel Management Center was unveiled and put into use[40]；On April 20, the installation and commissioning of the lighting system of the Dalian Bay subsea tunnel were completed[41]；On April 23, the asphalt paving of the land project on the south bank of the Dalian Bay subsea tunnel was completed, marking that the whole south bank of the Dalian Bay subsea tunnel is ready for traffic[42]；From 0:00 on April 26, the whole road network on the south bank of Dalian Bay subsea tunnel was opened[59]；On April 28, the Dalian Bay subsea tunnel passed the completion acceptance[43]；On May 1, the Dalian Bay subsea tunnel was opened to traffic[4]。
On April 30, 2024, the Dalian Bay Subsea Tunnel and Guangming Road Extension Project Dongfang Road Flyover will be put into trial operation, marking the opening of the whole line of the Dalian Bay Subsea Tunnel and Guangming Road Extension Project[65]。
Tunnel location
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The Dalian Bay subsea tunnel is located in Dalian, Liaoning Province, China, connecting Zhongshan District and Ganjingzi District;The tunnel starts from the entrances and exits of Renmin Road, Minzhu Square and Ganglong West Road, Donggang Business District, Dalian, Zhongshan District in the south, goes northward through the sea area of Dalian Bay, and ends at No. 20 Road, Barracuda Bay, Barracuda Bay, Dalian in the north;A pair of two lane ramps is set on the north bank of the tunnel to connect with Barracuda Bay Road 20, a pair of two lane ramps is set on the south bank to connect with the direction of Democracy Square on the west side of CITIC Harbour City, and a pair of two lane ramps is set on the west side of Gangwan Bridge on Ganglong West Road to connect with the direction of Gangwan Square[1][44]。
South bank of tunnel
Tunnel design
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Tunnel structure
Overall layout
The Dalian Bay subsea tunnel is composed of subsea immersed tunnel section, land section and connecting line road section. The main section of the tunnel is arranged in a north-south direction[45]。
Design features
The Dalian Bay subsea tunnel is the first cross sea immersed tunnel project in China to be constructed by dry dock method. The immersed tunnel section adopts the form of two holes and one pipe gallery. The middle pipe gallery is divided into four layers, namely, smoke exhaust passage, cable passage, safety passage and water pipe trench;The dry dock prefabrication area is symmetrically divided into two independent chambers in the east and west, and each chamber prefabricates three immersed tubes at the same time[46-48]。
Cross section of Dalian Bay subsea tunnel
Tunnel parameters
The main structure of Dalian Bay subsea tunnel has a total length of 430m, including 380m buried section and 50m open section[8]。The main body is composed of 18 immersed pipes. The standard pipe section is 180 meters long, 33.4 meters wide, 9.7 meters high, and weighs about 60000 tons after prefabrication;E5 pipe joint, 22.5m long[10]；E14 pipe joint has a total length of 148 meters, a straight section of 96.8 meters, a curve section of 51.2 meters, a width of 33.4 meters, a height of 9.7 meters, and a weight of about 47000 tons[25]；The final butt joint is 25 meters long, 36.23 meters wide, 12.7 meters high, and 6.9 meters clear of the driving hole[21]。
The main line of the buried section of the Dalian Bay subsea tunnel is 640 meters long, including 25 structural sections;D. The total length of E ramp is 691.7m[23]；The main line of the main structure section of the land project is 476m long, the ramp is 150m long, and Renmin Road is 425m long, which is divided into 62 structural sections[57]。
The dry dock of Dalian Bay subsea tunnel is 260 meters wide in the south, 360 meters wide in the north, and 580 meters long, covering a total area of 249000 square meters[6]A single dock is 480 meters long, 135 meters wide in the north, 74.7 meters wide in the south, and covers an area of about 110000 square meters. The west dock prefabrication yard is about 500 meters long, 135 meters wide, and 15 meters deep[11]；The north bank project is 330 meters long. The main line of the tunnel is grounded at the north side of Renmin Road and connected with the ground road, with a length of 1392 meters[8]。
Tunnel North Bank[60]
technical standard
Road grade
Urban expressway
Design speed
Main line: 60 km/h, ramp: 30-40 km/h
Lane setting
Two way six lane
Design load
City Level A
design period
100 years
Safety level
class a
Fire resistance rating
class a
Seismic grade
Fortification according to VII degree
reference material[50]
Equipment and facilities
Management Center
Dalian Bay subsea tunnel is equipped with a management center with a total building area of 6322 square meters, including the first underground floor and the fourth ground floor. With multi-source data and a variety of scenarios, it meets the needs of unified management, centralized monitoring, comprehensive analysis, emergency linkage and other work for tunnel operation, providing efficient, convenient, digital and intelligent services for the tunnel[40]。
Management Center
power supply system
One lighting distribution room and emergency lighting power supply room are respectively set in the north bank equipment area, the south bank equipment area (I) and the south bank equipment area (II) of the Dalian Bay subsea tunnel. In addition, two lighting equipment platforms are set in the immersed section of the tunnel.The lighting distribution room is equipped with lighting distribution cabinet, intelligent lighting control cabinet and lighting distribution box in equipment area. The emergency lighting power supply room is equipped with centralized emergency power supply device and A-type emergency lighting centralized power supply. The lighting equipment platform is equipped with 10 kV/0.4 kV dedicated buried transformer for lighting, lighting distribution cabinetIntelligent lighting control cabinet, centralized emergency power supply device and centralized power supply for A-type emergency lighting[49]。
lighting
The Dalian Bay subsea tunnel is equipped with a subsea lighting system. Artificial intelligence lighting can achieve harmony and unity with natural light, and can "feel" the sunny, cold and warm, night and day. It can not only adapt to the changes in light perception throughout the year, but also timely adjust the color temperature and color difference between the seabed and the land. It can also be based on different weather conditions such as sunny, cloudy, rainy and snowy days, foggy days, and early morning, evening, daytimeAt night and other different light intensities, timely adjust the brightness of seabed lights[49]。
Interior view of submarine tunnel
Operation
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Ticket system fare
As of May 2023, the Dalian Bay subsea tunnel is a purely public welfare municipal infrastructure. During the entire operation period, no fees will be charged for social vehicles[50]。
Passage
Trucks (except pickup trucks), special trucks for carrying goods, concrete mixer trucks, concrete pump trucks, truck cranes, trailers (except recreational trailers), dangerous goods transport vehicles and motorcycles, non motor vehicles (including electric bicycles), pedestrians are prohibited from passing through the Dalianwan subsea tunnel[51]。
Construction achievements
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Technical difficulties
construction technique
The main construction technology adopted in the construction of Dalian Bay subsea tunnel is the subsea highway immersed tube tunnel construction method[44][50]。
Access to subsea tunnel[61]
Construction difficulties
During the construction of the Dalian Bay subsea tunnel, the main difficulties and characteristics are as follows:
one
The Dalian Bay subsea tunnel project has many new tests, such as small tunnel curve radius, test of concrete durability in cold sea areas, and complex navigation conditions. It is difficult to construct and requires high quality.
two
The construction area of E1 pipe joint of Dalian Bay subsea tunnel is rock foundation, and the geological condition is poor, so it is impossible to use the full lift conventional leveling vessel to insert piles.
three
Dalian is located in the northeast of China. The cold weather in winter will bring many inconveniences to the construction, which is a great test for both ship equipment and construction personnel.
four
The geology of the construction sea area of the Dalian Bay subsea tunnel is complex and changeable. The geological pipe joints are all over the karst ditches, karst troughs, boulders, stalagmites, and the middle is also mixed with rich red clay.
five
There are many submarine karst caves and gullies in the construction sea area of Dalian Bay subsea tunnel, and the rock foundation fissures are developed. Five of the 18 immersed tubes are located on the clay layer.In this part of construction, the clay shall be excavated, the gravel shall be filled again, and the sinking pipe can be installed only after the compaction and leveling.
six
The waters of Dalian Bay are narrow and the navigation conditions are complex. Passenger ships, cargo ships, etc. frequently come and go. During the peak period of offshore construction, there are more than 100 ships, but the construction period is only 50 months, which brings great challenges to construction safety and maritime navigation capacity[44][50]。
seven
As the foundation of Dalian Bay Subsea Tunnel Management Center is located in the moderately weathered dolomite stratum, its hardness is 5 times that of ordinary concrete.The constructor took the foundation pit excavation as the starting point, organized the technical personnel to demonstrate repeatedly, and finally decided to adopt the rock hammer method for excavation, construct in sections and sections, strengthen the process connection, and refine the quality control. It only took 30 days for the foundation pit excavation to be completed as planned.The curtain wall is designed to be hung and installed with green natural marble and clay bricks.During the construction, the builders skillfully used aluminum alloy lining plates and adjustable pendants to solve the problems such as poor flatness and inconsistent butt joints of a large number of loose parts when they were hung and installed, effectively avoided the construction quality problem of mutual extrusion cracking caused by too many pendants, and realized the accurate installation of each part[63]。
Dalian Bay subsea tunnel under construction
technological innovation
"Jacking segment method" process
The construction technology of the final joint of the immersed tube tunnel of the Dalian Bay subsea tunnel has innovatively adopted the "jacking segment method" for the first time in China.Compared with other construction methods, the whole work of the jacking segmental method process is completed in a dry ground environment, which has the advantages of simple structure fabrication, guaranteed construction quality, short construction period, low construction cost and strong safety[44][50]。
Sinking dry dock "processing plant"
The Dalian Bay subsea tunnel has built the largest dry dock "processing plant" for immersed pipes in China to prefabricate immersed pipe segments in the dry dock.The dry dock is divided into east and west dock chambers. Each dock chamber needs to prefabricate 3 immersed tubes in each batch. A total of 3 batches need to be prefabricated to ensure the construction period of the project.The 180m immersed tube is divided into 8 small sections. Each small section adopts the whole section one-time casting molding process, which can effectively reduce the possibility of concrete cracks.As one of the core technologies of the sinking pipe prefabrication process, the complete set of large-scale full-automatic hydraulic formwork used in the fabrication process is equipped with machine-made sand for sinking pipe concrete, which has large volume, high precision requirements, and complex installation and adjustment process[44][50]。
Pipe sinking dry dock prefabrication yard[58]
Preparation of concrete with artificial manufactured sand
Dalian is a frozen area in the north, and the marine environment conditions are bad.The builders of the Dalian Bay subsea tunnel have fully investigated the existing coastal projects in Dalian area, sampled and analyzed the marine concrete such as the wharf that has been used for less than 90 years, conducted thousands of tests, and obtained valuable basic data, filling the blank in the research of the durability of hydraulic concrete in Dalian area.On the basis of these massive works, with reference to the statistical data of Japan and South Korea, the research theory of concrete durability in Europe and the United States, which are commonly used internationally, has been further innovated and developed.In order to protect the "green water and green mountains" and the natural ecological environment, the tunnel builders have done a lot of experimental research in the early stage of this project, and formulated corresponding special standards. The concrete is prepared with artificial machine-made sand, realizing the harmonious development of man and nature[44][50]。
Construction of "Digital Project"
Dalian Bay Submarine Tunnel innovatively implements the construction of "digital project", carries out digital project construction in the process of physical project construction, applies BIM technology, Internet collaboration technology, and Internet of Things technology to the full life cycle of design, construction, operation and maintenance of Dalian Bay Submarine Tunnel, and improves project construction quality, construction management, and operation and maintenance management,Finally realize the handover of "physical engineering+digital engineering" dual products[44][50]。
Scientific research achievements
As of September 2022, 197 patents have been applied for the Dalian Bay subsea tunnel project, including 77 invention patents, and 2 achievements have reached the international advanced level[52]。
Honor recognition
Award time
Honors won
Organizer
2022
National major highway project news publicity "excellent project"
The Dalian Bay subsea tunnel is the first to build large cross sea immersed tunnels in cold regions in China, forming the core technology with independent intellectual property rights, powerfully promoting the progress of China's cross sea immersed tunnel construction technology, and contributing China's strength to the construction of immersed tunnels in the world[1]。(Sun Zhuping, Deputy Chief Engineer of Dalian Bay Subsea Tunnel Co., Ltd.)
After the opening of the Dalian Bay undersea tunnel, a new north-south fast track will be added to Dalian, which is of great significance in easing traffic congestion in the central urban area of Dalian, expanding urban development space, and promoting the integration of the two sides of the Dalian Bay[3]。(Xinhua Online Review)
Following the Hong Kong Zhuhai Macao Bridge, the Dalian Bay subsea tunnel is another cross sea transportation cluster project with complex technical conditions and high environmental requirements.This traffic artery connecting the north and south sides of Dalian Bay connects the main city of Dalian with Ganjingzi District, Jinpu New Area and other major regions, bringing new opportunities for the industrial development and population development of Dalian[54]。(CCTV News Review)
Aerial photography of the south bank of the tunnel[60]
The completion of the Dalian Bay Submarine Tunnel will effectively break the traffic bottleneck formed by the "C" shaped spatial structure of Dalian, add a new fast channel for Dalian that runs from north to south, connects the core area in the east of Dalian and Jinpu New Area, and make the "Cape of the Sea" open to traffic. It is of great significance to alleviate traffic pressure, optimize urban ecological functions, and promote the integration of the two sides of the Dalian Bay[55]。(commented by Economic Daily)
When completed and put into use, the Dalian Bay undersea tunnel will become an important channel connecting the central city, Ganjingzi District and the development zone, providing a new channel for vehicles from the Dalian Bay area, the Spring Residential Area, Jiaojinshan Residential Area, the Barracuda Bay New Area, the Diamond Bay, and the Xianglu Reef Logistics Park to get in and out of the central city of Dalian, which is of great significance to improving the regional transportation system[56]。(Review of Peninsula Morning Post)
The official opening of the Dalian Bay undersea tunnel will reconstruct the overall road traffic pattern, reshape the urban development layout space, provide strong support to meet the needs of the masses for convenient travel, create an international landmark dynamic bay area, and accelerate the construction of an international comprehensive transportation hub city[61]。(Grand View News Review)
The Dalian Bay Submarine Tunnel, a pioneering project of immersed tube tunnel construction in the cold sea area of China, has effectively solved the traffic bottleneck of Dalian's C-shaped structure, connecting the prosperous Zhongshan District with Ganjingzi District, which has great development potential, and has put wings on Dalian's development[62]。(Northeast News Online Review)
