China has announced the development of the world's first Tunnel Boring and Blasting Machine (BBM), aiming to make tunneling operations faster and safer in challenging underground conditions. The new system combines traditional Tunnel Boring Machine (TBM) technology with controlled blasting in a single machine.
Named "Xianglong," the 400-ton machine can excavate tunnels approximately 70 meters long and 4.55 meters in diameter. The machine rolled off the production line on Saturday at the manufacturing facility of China Railway Science & Industry Group (CRSIC) in Wuhan, Hubei province, China.
The BBM was jointly developed by Tsinghua University and China Railway Science & Industry Group. CRSIC, a subsidiary of China Railway Group, integrated the advantages of TBM technology with traditional drilling and blasting methods into the system. Chinese officials consider the developed system a significant advancement, especially for large-scale tunneling projects in complex geological conditions.
Adapts to Challenging Ground Conditions
Large tunneling projects often encounter severe problems such as soft and deformable rocks under pressure, sudden rock bursts, flooding, and mudflows. Such conditions both slow down excavation work and pose significant risks to occupational safety.
While traditional drilling and blasting methods require extensive safety precautions, classic TBMs used for hard rock may not be flexible enough in areas where ground conditions change abruptly.
The BBM aims to solve this problem by combining the advantages of these two methods into a single system. The machine can switch between different excavation methods depending on the rock conditions encountered.
The system can transition between different operating modes, including blasting first then excavation, excavation first then blasting, and full-face TBM excavation. This allows a single machine to adapt to varying geological conditions along the tunnel.
Different Excavation Methods with a Single Machine
One of the most striking features of the BBM is its hollow cutter head design, which works in conjunction with a central cutter head. This structure eliminates the need for operators to change equipment to switch between different excavation methods. According to the China News Service, the system could help solve some long-standing problems in tunneling operations in complex terrains.
Qin Pengxiang, a researcher at Tsinghua University's State Key Laboratory of Hydroscience and Engineering, stated that in laboratory tests, the BBM could increase excavation efficiency by 30 percent compared to traditional TBMs.
Special Protection Against Blasting
The machine's design focuses not only on excavation performance but also on safety and tunnel support systems. The BBM features retractable side cutters that can change the excavation width. These cutters also facilitate the machine's passage through previously completed tunnel sections.
Furthermore, an adaptive telescopic tail shield allows for the use of different-sized tunnel lining segments. This feature makes it possible to apply variable-diameter tunnel linings in areas where rock bursts or large-scale ground deformations occur.
A blast-resistant protective shield is also used to protect the machine's sensitive components during blasting. The system also has two independent conveyor belts that transport excavated rock and aggregates for construction separately.
First Use in a Hydropower Plant Project
Chinese officials state that the BBM and its core components were developed with completely independent intellectual property rights. The world's first drilling and blasting machine will initially be used for demonstration purposes in a pumped-storage hydropower plant's tunnel project. The field data obtained during this process will be used to further improve the machine's performance.
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