Technical Seminar on Prevention and Control of Rockbursts in Railway Tunnel under High in-situ stress was held by the CSRME

On May 31, 2022, a technical seminar on the prevention and control of rockbursts in railway tunnels under high in-situ stress was held online. The organizers include the "S&T Innovation" of Rock Mechanics and Major Projects - State Key Laboratory Science and Technology Innovation Consortium, Chinese Society for Rock Mechanics and Engineering, CZ Railway Engineering Headquarters of China Railway Engineering Group Limited, State Key Laboratory for Geomechanics and Deep Underground Engineering. 

Academician Manchao He, the President of the CSRME, Mr. Jun Wu, the Director of the Department of Science and Technology Innovation and Digitalization of China Railway Engineering Group Limited, Professor Xiaojie Yang, the Secretary-General of the CSRME, Mr. Tingya Wen, the Chief Engineer of CZ Railway Engineering Headquarters of China Railway Engineering Group Limited, Mr. Kairong Hong, the Chief Engineer of China Railway Tunnel Group, and nearly 400 people from Engineering Branch of China Railway Society, China Railway Corporation Limited and China Railway First Group, Second Group, Third Group, Fourth Group, Fifth Group, Eighth Group, Tenth Group and Tunnel Bureau attended the seminar.

At the meeting, Mr. Jinhu You, the Chief Engineer of the 2nd Bid Project of CZ Railway and the Department of China Railway Tunnel Group, reported the rockburst prevention and control technology in TBM tunnels from five aspects: engineering background; engineering progress; rockburst prevention and control; TBM targeted design, problems and thinking. Mr. Zeng Yang, the Deputy Chief Engineer of the 3rd Bid Project of CZ Railway and the Department of China Railway Fifth Group, reported the key technologies for rockburst prevention and control by drilling and blasting in Sangzhuling Tunnel of Lalin Railway from three aspects: tunnel construction; key technologies for rockburst prevention and control; and experience summary. Associate Professor Dongqiao Liu from the State Key Laboratory for Geomechanics and Deep Underground Engineering systematically introduced the rockburst mechanism and its control technology from six aspects: rockburst phenomenon; rockburst mechanical mechanism; rockburst experimental system and rockburst experiment; rockburst control countermeasures; application examples; and main conclusions.

As regards the problems encountered in the prevention and control of rockburst for railway tunnels under high in-situ stress, all the experts at the meeting had an in-depth discussion, and raised the following 23 key questions: (1) Are rockburst and brittle fracture the same problem? (2) What are the types of rockburst? (3) What are the grades of rockburst? (4) How to interpret the mechanism of rockburst? (5) Is it true that only hard rock can burst? (6) What are the criteria of rockburst? (7) What are the advantages of NPR materials used in rockburst prevention and control? (8) What are the structural surface effects and dynamic load failure problems of rock bursts? (9) What is the difference between active support and passive support? (10) Can the use of NPR materials control the rockburst in TBM excavation? (11) Why should add three advanced systems for the rockburst NPR-TBM, namely advanced electronic detection, advanced grouting, and advanced reinforcement? (12) What is the effect of the application of NPR anchor bolts in the Yinhanjiwei project? (13) How should excavation compensation be made during rockburst? (14) How do we consider when the structural surface exists? (15) What is the anchoring principle of NPR anchor cable? (16) How to predict the occurrence time and treatment of rockburst? (17) Can it be prevented by stress release when there is a large mass of rockburst caused by bad geological structures? (18) What is the effect of the use of NPR on rockburst? (19) What is the effect of advanced stress release on rockburst? (20) What is the effect of pressure relief by water injection on rockburst? (21) Can we predict rockburst? (22) Can hydraulic fracturing technology control rockburst? (23) Is it possible to develop plastic NPR materials considering the cost? For the above 23 questions, Academician Manchao He gave detailed answers one by one. He puts forward suggestions for guiding the prevention and control of rockburst in railway tunnel construction under high geo-stress from the aspects of rockburst formation mechanism, classification, occurrence time, and influence factors. He also elaborated on the difference between rockburst and rock brittle facture, the influence of faults and structural surfaces on rockburst, the stress transformation mechanism during tunnel excavation under high geo-stress, the "Method, Instrument and Technology" of hard rock rockburst prevention and control, stress compensation-based tunnel support design and construction, and theoretical basis of constant resistance large deformation function for NPR anchor bolt/cable. In addition, he introduced the application effects of new materials and new technologies for rockburst prevention and control in tunnels, underground projects, and diversion tunnel in the Yinhanjiwei project. The engineering technicians and experts who attended the seminar gave high praise for Academician He's scientific spirit, his explanations in simple language, easy-to-understand and methods to solve practical problems.

Mr. Jun Wu, the Director of the Department of Science and Technology Innovation and Digitalization of China Railway Engineering Group Limited, puts forward the general guidelines "focusing on cutting-edge technology, technical support, change of mind, courage to innovate, safety guarantee, and comprehensive measures", adhering to the construction of projects empowered by science and technology, and realize rockburst treatment from "prevention" to "Control". Mr. Tingya Wen, the Chief Engineer of CZ Railway Engineering Headquarters of China Railway Engineering Group Limited,  pointed out that the rockburst in CZ railway hard rock tunnel under high geo-stress is an obvious problem, and all participating units should strengthen communication with the expert team of scientific research institutes, and actively seek the prevention and control measures combining active support and passive protection, and develop new technologies, new methods, and new equipment with higher application value, in order to construct the Sichuan-Tibet Railway into an innovative and safety engineering.

Finally, the host Mr. Kairong Hong made a summary, and he believed that this seminar built an academic and technical exchange platform for industry-university-research applications, improved the technical level of rockburst prevention and control for tunnels under high in-situ stress, and laid a good foundation for the safe and efficient construction of the CZ railway.