China has introduced the world's first machine for drilling and undermining tunnels. This equipment combines a tunnel boring machine with a system capable of using explosives to pass through rock formations.
The machine is named Xianglong, which translates to 'Happy Dragon.' It was developed by the China Railway Science and Industrial Research Group (CRSIC) in Wuhan and Tsinghua University. According to state media Xinhua, this machine can increase the efficiency of earthworks by 30%.
Traditionally, tunnel boring machines are designed to operate under specific conditions. There are models intended for soils such as clay, sand, and gravel, as well as others designed for hard formations like granite, basalt, and sandstone.
A problem arises when these two types of conditions alternate during construction. This is the type of terrain for which the Xianglong is designed to work.
The equipment has a diameter of 4.5 meters and is equipped with a cutting head with a central hole. It can partially retract into a protective casing that shields the components and sensors located behind it.
The system integrated into the cutting head allows for drilling several meters into the rock. The drilled holes are filled with low-energy, high-speed explosives, which are then sealed with sand or clay.
Upon detonation, they cause micro-cracks in the rock mass. The goal is not to eject large pieces of material far away. The protective casing helps absorb and deflect the force generated by the explosion.
After blasting, the cutting head returns to its position and begins crushing the fragmented rock.
In practice, this process involves several stages. Xinhua reports that the Xianglong can increase the efficiency of earthworks by 30% compared to traditional machines. Furthermore, the protective casing can vary in diameter to accommodate different segments used for tunnel lining.
The main idea is to avoid stopping work or needing to fundamentally change the approach due to geological changes. Instead of relying solely on mechanical destruction, the machine can resort to blasting when encountering a more stable mass.
However, there is an important caveat: although the Xianglong has been built, it is not yet known how the system will perform in real operating conditions. The efficiency claimed by the manufacturer and the ability to overcome sections with varying characteristics still need to be proven in practice.