Chinese scientists have developed the world’s first tunnel boring and blasting machine (BBM), which can increase performance by over 30% when drilling through ultra-hard rock.
Chen Jiale, a researcher at the China Railway Science and Industry Group (CRSIC), stated that the machine will be used in hydropower and irrigation projects, mining, highway, and railway construction, as reported by Interesting Engineering on May 22. “The development of the tunnel boring and blasting machine can address many current challenges in constructing long and large tunnels, providing a new solution for such projects,” Chen shared.
Tunnel boring and blasting machine at the production facility. (Photo: CRSIC).
Not only does BBM possess the power of modern tunnel boring machines, but it also combines mechanical, electrical, hydraulic, sensor, and navigation technologies, allowing for the simultaneous use of traditional drilling and blasting methods. The machine is equipped with dual cutting heads and takes advantage of the complementary benefits of each method, enhancing efficiency and being environmentally friendly. According to Chen, “this design effectively combines the functions of a tunnel boring machine (TBM) with traditional drilling and blasting methods, incorporating various earth excavation modes.”
BBM has completed testing under three different operating conditions. Test results indicate that under ultra-hard rock conditions, the performance of the hollow cutting head can increase by 30% after pre-cracking treatment. A limitation of conventional TBMs is their tendency to become stuck and slow progress when encountering complex geological conditions such as sudden rock collapses, fault zones, and significant deformation in soft rock layers.
BBM, co-developed by CRSIC and the National Hydrology and Engineering Laboratory of Tsinghua University, can handle a wide range of complex geological conditions. For example, if BBM encounters a large fault zone, a smaller device can pre-treat the area using BBM’s circular cutting head. In cases of sudden mud or water influx, BBM can use the circular cutting head to dredge and remove mud, followed by foundation treatment and waterproofing.
Chen emphasized three key features of BBM, including the hollow cutting head that provides a pathway through unfavorable geological conditions for pre-treatment, avoiding redirection. The dual-mode operation of BBM, integrating both drilling and blasting methods, allows for simultaneous excavation and blasting. This approach combines the safety and efficiency of TBMs with the flexibility of the two methods.
Finally, when surrounding rock conditions are favorable, the central rock mass can be used to produce aggregate on-site (natural or artificial loose material with a defined grain composition that, when mixed with cement and water, forms concrete), reducing project costs and promoting green construction. According to researcher Qin Pengxiang from Tsinghua University, BBM has extensive application value and great potential.
CRSIC, part of the China Railway Group, contributes to the development of heavy construction equipment used in some of the country’s most challenging infrastructure projects. The company, headquartered in Wuhan, the capital of Hubei Province, has manufactured large shield tunnel boring machines such as the Jiangcheng Pioneer, as well as Lu Wu, the first domestically produced 1,000-ton single beam bridge erecting machine, a 2,000-ton dual-girder crane with the highest lifting capacity in the country, and Yuehai, the world’s largest 1,800-ton box girder erecting machine.
