China's Secret Tunnel Weapon: Hybrid Machine Merges Blasting and Boring

Engineers in China have developed the world's first Blast Boring Machine (BBM), a hybrid tunneling device that combines mechanical drilling with controlled explosions. The system is designed to increase excavation speeds by 30% when working in unstable ground conditions where traditional equipment often fails due to risks of collapse or sudden mud inflows.

The project was realized through a partnership between the China Railway Science and Industry Research Institute (CRSIC) and researchers from Tsinghua University. The goal was to eliminate the choice between slow drill-and-blast methods and high-speed tunnel boring machines (TBMs), as standard TBMs frequently face accidents when encountering soft rock and water-bearing layers.

Technical Design and Mechanism

To integrate explosives into a boring machine, engineers redesigned the internal architecture to protect electronics and hydraulics from the vibration loads generated by detonations occurring directly in front of the cutting head. The BBM features an automated system for placing explosive charges into the rock.

A reinforced armor shield is the central component that protects the machinery from its own blasts, absorbing the primary shock wave so that operations can resume immediately after a detonation. The rest of the complex functions like a standard high-tech TBM: two conveyor belts continuously remove debris while a robotic manipulator installs concrete tunnel walls.

Field Implementation and Safety

The first prototype has left the factory in Wuhan. According to geologist Aleksey Trofimov, this hybrid approach minimizes the risk of sudden collapses because the explosions controllably release tension within the rock strata. By automating the process at the face—the most dangerous zone of a tunnel—the machine removes personnel from high-risk areas.

The first BBM is slated for use in constructing water conduits for a pumped-storage hydroelectric power station. Beyond this, China intends to mass-produce these shields for projects involving mountain ranges with complex hydrology and strategically important high-altitude railways.

Questions about the Tunnel Blaster

Do the explosions damage the tunnel structure?

The system utilizes micro-charges and directed detonation, ensuring that only the rock directly in front of the shield is destroyed without damaging the concrete lining already installed.

Is the machine fully autonomous?

While the installation of walls and debris transport are automated, operators still control the placement of explosives and monitor ground conditions.

Why not use a standard TBM in soft rock?

In unstable formations, conventional shields can become stuck or trigger collapses. Preliminary loosening via explosion makes the rock more malleable and predictable.

Source: This article was adapted from an original Russian-language publication by Pravda.Ru.