The "Qiangguo" super-large diameter tunnel boring machine has new functions!

On November 20, the ultra-large diameter slurry shield machine "Qiangguo" jointly built by China Railway 22nd Bureau and China Railway Construction Heavy Industry was prepared to be shipped to the "Qianhai to Huanggang Port Section Three Work Area" project of the Guangzhou-Shenzhen-Dongguan Intercity Railway in the China Railway Construction Heavy Industry Park.

Image provided by China Railway 22nd Bureau Group

The "Qiangguo" is currently the most advanced super-large diameter shield machine in China, and is known as the "ceiling" and the culmination of similar products. What are the new features of the "Qiangguo"?

"'Qiangguo' is 126 meters long and weighs 3,300 tons. It uses a normal-pressure composite cutterhead and is equipped with the most advanced electrical system and mud-water circulation system in the country. The excavation diameter is 13.27 meters, and many of its configurations are the best in the country. At the same time, it is the first time that a tunneling and excavation management system has been used in China, which has greatly improved the level of intelligent operation of the shield machine. Through precise analysis and accurate calculation of the amount of earth produced during tunneling and excavation, the problem of over-excavation of the shield machine can be effectively avoided." said Liu Ziming, person in charge of the Guangzhou-Shenzhen-Dongguan Intercity Project of the Rail Branch of China Railway 22nd Bureau Group.

Image provided by China Railway 22nd Bureau Group

It is reported that the shield tunnel in the third work area of ​​the Qianhuang section of the Guangzhou-Dongguan-Shenzhen intercity railway is the first large-diameter shield tunnel in Shenzhen's intercity railway. "The shield tunnel section is 3,511 meters long and is a double-track tunnel with the characteristics of large excavation section, poor geological conditions, high construction standards, and many key technologies. There are 28 medium and high risk sources along the line, more than 100 pipelines underpass, and multiple cross-overs, underpasses, and parallel existing lines. The construction difficulty is second to none in domestic shield construction." Liu Ziming said that the stratum under the shield machine is a marine alluvial to alluvial plain landform, close to Shenzhen Bay and Shenzhen River, and underpasses Xinzhou River. The site belongs to the land reclamation area with dense buildings. In this case, the shield tunneling operation is like digging a tunnel in a "tofu block".

However, when using a super-large diameter shield machine to excavate in soft upper and hard lower strata, it is very easy to encounter problems such as surface settlement and tool wear. How to control the excavation parameters, judge the tool wear and the condition in the chamber in soft upper and hard lower strata has become the biggest difficulty in shield construction management.

Faced with the challenge, China Railway 22nd Bureau Group, in conjunction with the R&D team of China Railway Construction Heavy Industry, has specifically equipped the "Qiangguo" with a number of intelligent and humanized innovative designs.

In order to address the problems of uneven rock mass, developed cracks, and large differences in crack density and filling conditions in some areas, a slurry shield machine was selected in the design, which transports debris through closed-circuit pipelines, greatly improving the sealing performance.

In the design of the shield machine cutterhead, the R&D team adopted a highly wear-resistant and impact-resistant design. "The opening in the depth direction adopts an inverted cone design, that is, a 'strict in and wide out' structure." Liu Ziming said that this design is conducive to the entry of slag into the mud water tank, achieving the goal of improving the flow efficiency of slag, and then reducing the wear rate.

The "Qiangguo" is equipped with a series of top intelligent systems and has the "strongest brain".

"Each roller on the cutter disc is equipped with a series of devices including sensors, simple information pop-up windows and alarm systems." Liu Ziming said that each cutting tool is like having "eyes and ears" to ensure that the operator can obtain information such as the tool's working status and wear in a timely and accurate manner.

Construction operations and command are also all intelligent.

According to the technical staff, the intelligent grouting monitoring system uses detection radar and intelligent analysis software to realize automatic recognition of grouting images behind the tunnel wall, replacing the traditional judgment based on manual and experience, and realizing refined control of grouting behind the wall. At the ground shield command center, the technical staff uses the shield construction big data platform and intelligent data analysis system to realize functions such as intelligent project management, intelligent monitoring of equipment status, construction risk control, and intelligent auxiliary excavation.

"During excavation, 'Qiangguo' will also use a professionally designed control box to manage the communication and power supply of the total station, realizing true cable-free operation," said Liu Ziming.

It is reported that the 21.167-kilometer Guangzhou-Shenzhen-Dongguan intercity Qianhai to Huanggang Port section passes through Shenzhen Qianhai Cooperation Zone, Nanshan District, and Futian District. After completion, it will be of great significance to improve the intercity rail backbone network in Shenzhen's coastal area, support the rapid construction of key development areas such as the Qianhai Free Trade Zone and Dongguan Binhai New City, and build an intercity railway network in the Guangdong-Hong Kong-Macao Greater Bay Area.