Construction technology and manufacturing technology promote each other, my country's shield machine has grown from scratch, imported to export
"Underground Dragon" leads the way (Like these technological breakthroughs④)
Yu Sinan and Li Meihua
The shield machine, known as the "underground dragon", is a veritable great power tool.
Recently, the reporter walked into the site of the Beijing East Sixth Ring Road Transformation Project (hereinafter referred to as the Beijing East Sixth Ring Road Project). The largest diameter shield machine "Jinghua" developed by my country so far is operating here.
The builders of China Railway 14th Bureau manipulated it to excavate a 7.4-kilometer-long tunnel 30 meters below the ground, and at the same time tested the performance and construction technology level of the shield machine developed independently by my country.
Ten years ago, my country's shield machine mainly relied on imports, and even shield construction was difficult to complete independently.
More than ten years later, my country's shield machine has grown from scratch, from import to export, and has achieved a leap from "following" to "leading".
Beijing East Sixth Ring Road changed to underground, shield machine made 7.4km tunnel formed in one go
The East Sixth Ring Road passes through the core area of Beijing's sub-center. In order to facilitate transportation and integrate the city, the construction party put forward a bold idea: to change the East Sixth Ring Road from the ground to underground.
Two tunnels were designed for the reconstruction of the East Sixth Ring Road. Each tunnel has three floors and the excavation section exceeds 200 square meters, which is 5 times that of a general subway tunnel.
A shield machine with a conventional diameter is difficult to handle, and the 16.07-meter-diameter "Jinghua" rises to the challenge.
This is the first application of a 16-meter-class domestic shield machine in domestic construction.
The starting shaft of the "Jinghua" is located on the west side of the East Sixth Ring Road, from north to south, and the task is to dig a 7.4 kilometers long tunnel.
The reporter walked down the shaft safety ladder about 30 meters and arrived at the operation site of the shield machine.
"Jinghua" is about 150 meters long, like a small train, 5 groups of trolleys with different functions are connected in sequence, and the key components are integrated on the "locomotive"-No. 1 trolley.
The huge circular cutter head at the foremost end cuts soil and stones under the drive of a motor, and the tunnel extends forward from this.
The tunnel segment assembly is synchronized with the tunneling and slag discharge processes.
Every 2 meters of excavation is a construction cycle. The engineers put together the prefabricated segments into a complete circle, and the tunnel is formed at one time.
There is no leakage and no leakage of the segment joints, and the assembly precision is extremely high.
To build this tunnel, more than 3,600 rings need to be assembled, with a total of 36,680 segments.
Sun Xutao, head of the Beijing East Sixth Ring Project of the 14th Bureau of China Railway, told reporters that in the construction of domestic super-large-diameter shields, the "Jinghua" first applied double-liquid grouting technology.
Compared with a single cement slurry, the ratio of cement slurry and water glass into a two-liquid slurry, the slurry consolidation time is shortened from 8 hours to less than 1 hour, which greatly improves the tunnel forming effect.
Shield construction is revolutionary.
Gu Chuansheng, the deputy manager of the Beijing East Sixth Ring Project with more than 20 years of civil engineering experience, said with emotion: “In the past, the engineering team used to drill and fire, and dig a tunnel, which was very noisy and dusty. After a day’s work, he took off his cotton mask and it was dark. Yes; now, the working environment is open and bright, operating machines, transporting pipes, laying wires, and working efficiently and orderly."
From design to off-line, the "Jinghua" shield machine only took 6 and a half months
"Each shield machine is different." Chen Peng, a large shield expert at the 14th Bureau of China Railway, explained that due to the different soil layers, burial depth, and settlement requirements of the construction, there is no shield machine that can cover the world.
The "tailor-made" feature requires that the shield machine builder, manufacturer, and scientific research unit communicate repeatedly from the very beginning, and the tripartite cooperation runs through.
After winning the bid for the Beijing East Sixth Ring Project in 2020, the construction party, China Railway 14th Bureau, jointly manufactured Fangtiejian Heavy Industry, and completed the design, production, commissioning, and offline of the shield machine in just 6 and a half months.
This reflects the strong strength of my country's shield construction and shield machine development technology, and it is also a vivid practice of my country's concentrated strength to do major events.
"Compared with other shield machines, in addition to having a larger diameter, "Jinghua" also integrates years of innovations, indicating that my country's shield machine development and shield construction technology is becoming more mature." Chen Peng said.
my country's shield manufacturing started in 1953, and it was stagnated for a while due to backward technology.
In the 1990s, my country spent huge sums of money to introduce two shield machines for the construction of Qinling railway tunnels.
Since then, more and more shield machines have been used in infrastructure construction, but for quite a long time, my country has not only relied on imports for shield machines, but also on foreign teams for construction.
Chen Peng recounted the scene of domestic shield construction in the past: it was expensive to hire foreign engineers to debug equipment, install and repair parts.
Because the technology is blocked, Chinese personnel are not allowed to approach, let alone learning parameter calculation methods and equipment management concepts.
Technical personnel in our country explored and studied while constructing, and gradually mastered the basic essentials of shield construction through repeated operations, repairs, and maintenance.
In 2007, Chen Peng participated in the construction of the Nanjing Yangtze River Tunnel project that won the bid. This is the first time that a domestic construction team independently used a large-diameter shield machine in the Yangtze River Tunnel project.
Since then, my country's shield construction technology has advanced rapidly, and many technologies are now at the international leading level.
China's dependence on foreign shield machines has also been broken.
A conventional diameter shield machine weighs more than 3,000 tons and has more than 30,000 mechanical, electrical, hydraulic, pneumatic, and sensor components.
With so many components integrated together, how to ensure coordinated operation?
This has caused headaches for developers.
Sun Xuefeng, chief engineer of China Railway Construction Heavy Industry Roadheader General Plant, said that the development of shield machines requires the support of a huge inter-disciplinary, inter-professional, and inter-industry industrial technology system. The manufacturing process is complex, and there are thousands of design drawings alone.
In 2002, the development of shield machine was included in the "863 Program", led by China Railway Tunnel Group.
After years of research and production, the first shield machine with independent intellectual property rights was manufactured in my country in 2008.
In the meantime, my country's shield technology research team has grown stronger, including Zhejiang University, Huazhong University of Science and Technology and other scientific research institutions, as well as China Railway Construction Heavy Industry, Northern Heavy Industry, China Communications Tianhe and other manufacturers.
At present, the "Jinghua" has successfully advanced more than 400 meters, and multiple design indicators of the shield machine have been verified during construction.
This means that the largest diameter shield machine independently developed by my country has generally reached the international advanced level, and my country has achieved the leap from "following" to "leading" in shield machine development and shield construction technology.
Optimized generation by generation, the shield machine's atmospheric tool change technology has gone through four generations
Developed countries have hundreds of years of history in manufacturing shield machines. How can my country quickly catch up?
The answer of industry experts is: the mutual promotion of construction technology and manufacturing technology is the key.
Experts said that the continuous optimization of shield machine research and development technology, more from the continuous feedback from the construction.
Take shield machine tool change technology as an example.
What should I do if the tool is damaged during shield tunneling?
The traditional method is to change the tool under pressure, which requires cumbersome operations such as pressurization into the cabin and decompression out of the cabin, which is time-consuming, expensive, and also has safety risks.
During the construction process, the technicians put forward the idea of changing the tool under normal pressure.
In the Nanjing Yangtze River Tunnel Project, the construction team of China Railway 14th Bureau and the manufacturer adjusted the structure of the shield machine, developed and successfully tried the first generation of atmospheric pressure tool change technology.
In 2010, the Nanjing Metro Line 10 cross-river tunnel project under the charge of the China Railway 14th Bureau. Faced with complex geology and high water pressure, technicians and scientific researchers redesigned the tool-changing structural system and developed the second-generation constant Pressure tool change technology-sleeve cylinder type tool change technology, and for the first time applied in the 11-meter-diameter shield construction.
Tool change technology continues to improve and innovate in engineering practice.
In the excavation of the Wuhan Metro Line 8 project that won the bid in 2015, the construction team of China Railway 14th Bureau developed the gear hobbing interchangeable tool change technology for the first time in view of the geological conditions of the different lithological composite strata at the bottom of the river, which became the third generation of atmospheric pressure. Tool change technology.
According to reports, "Jinghua" is equipped with the fourth-generation atmospheric pressure tool change technology.
From under pressure to normal pressure, optimizing from generation to generation, this tool change technology, which is researched and developed and continuously improved from practice, has now become a regular option for the development of large shields.
“my country’s shield construction market has a large demand, and there are many types of geology encountered. It can continue to provide feedback to promote the rapid update and iteration of the independent research and development of shield machines.” Chen Peng said, for example, the super large diameter shield machine developed by my country in September 2017. "Yuan'an" is equipped with atmospheric pressure tool change. In the application of new technology, the domestic shield machine has quickly caught up with the international first-class level.
Abundant and diverse infrastructure construction requirements have also promoted the development of my country's shield products to small, micro, mega, and heterogeneous.
In addition to the large-diameter mud-water balance shield machine "Jinghua", domestically-made large-diameter earth pressure balance shield machines, large-diameter hard rock shield machines and other products have also rolled off the production line, creating a series of new tunnel excavation modes.
The improvement of the manufacturing level of shield machines, in turn, has opened up a broad market for the application of shield construction, and has shown its skills in railway engineering, water conservancy engineering, urban renovation and other fields.
The domestic shield machine went out and became a beautiful business card made in China
The leapfrog development of my country's shield machine equipment has led to the leap of supporting industries.
Sun Xutao told reporters that taking knives as an example, the knives equipped with domestic shield machines were basically imported before 2015, and now the domestically-made knives are not inferior to international brands.
Statistics show that the domestic market share of domestic shield machines has exceeded 90%, and the global market share is close to 70%.
The domestically-made shield machine that went out has become a beautiful business card made in China.
According to expert analysis, China's sophisticated management and construction standards were exported together with large-scale equipment, forming a "Chinese brand".
"Just like a good car needs to be driven by someone who knows the car, operating a shield machine is also a technical job." Sun Xutao said.
In August 2018, the Sutong Yangtze River GIL comprehensive pipeline tunnel project was completed. The shield machine used by China Railway 14th Bureau has a good rate of over 97%. clear and distinct.
The refined management and maintenance have made foreign parties admire.
Relying on excellent quality and technology, my country's shield tunneling machine has shown its skills overseas.
Nowadays, in the Singapore market, which is known for its high standards, the shield machine produced in China has left a shadow in the transportation construction; the Italian company purchased the shield machine from my country and successfully constructed the Lebanon Great Beirut water supply project; in Denmark, France and other countries In underground engineering, Chinese shield machines are also being used more and more.
"Intelligence and automation are the development direction of shield technology in the future." Chen Peng said that in the Beijing East Sixth Ring project, engineers are trying to build smart construction sites. The construction process is combined with the Internet of Things and big data to implement refinement, Process-oriented and intelligent management will further improve my country's shield construction capabilities.