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TBM (Full Face Tunnel Boring Machine) tunneling method has significant economic and technical advantages and is becoming an innovative method for deep roadway speedy construction. However, due to the special complex geological conditions and construction environment of coal mines, the technical challenges faced by TBM tunneling in deep roadways and the key scientific problems are analyzed: ① adaptive design of TBM equipment and the mine system under special tunneling environment in coal mine is difficult to fulfill; ② the rock fragmentation mechanism in soft and hard mixed strata is unclear, and the efficient rock cutting is difficult to realize; ③ The risk of soft rock squeezing deformation and TBM jamming, and the difficulty for accurate prediction and safety control is large; ④ Due to the narrow tunneling space and the serious interference of dust and water fog, it is difficult to monitor the tunneling process and make decision control and disaster warning according to the monitoring information. In this regard, systematic research on adaptive equipment design, efficient rock cutting in mixed-ground, squeezing deformation and TBM jamming disaster prediction and control method, and intelligent assisted tunneling method in deep composite stratum tunneling has been carried out. Research results on the TBM safe and efficient tunneling technology are achieved: ① the present situation of TBM adaptive design technology for special construction environment of coal mine is illustrated. ② full-size disc cutter penetration and linear cutting tests for hard and soft rock under high confining pressure are performed. Accordingly, the influence of complex geo-stress, rock strength and lithology change, tunneling control mode,cutter installation radius on the TBM cutting efficiency and rock fragmentation mechanism are revealed. The evaluation and prediction method of TBM tunneling performance and the corresponding rock mass classification method in deep mixed ground is put forward. ③ The mechanism of large deformation and TBM jamming disaster during TBM tunneling in deep coal measure soft strata is revealed. The FDEM (combined FEM and DEM) numerical simulation method of large deformation and TBM jamming disaster evolution and corresponding control measures for TBM tunneling in soft rock is developed. The monitoring and warning method of squeezing deformation and TBM jamming disaster is put forward. A comprehensive prevention and control technology system of ‘large diameter over excavation, excavation parameter optimization and step by step combined supporting’ is proposed for large squeezing deformation and TBM jamming hazard. ④ The real-time sensing technology of rock-TBM interaction information (cutter head - roadway face interaction, surrounding rock-shield interaction) in TBM tunneling process is proposed, and the adaptive intelligent decision-making method for advance parameters is initially developed. The research progresses will promote the application of TBM tunneling in coal mine roadway construction and safe and efficient tunneling technology.

To better understand the rock fragmentation mechanism and optimize cutter design and selection for rock excavation by TBM, a set of three-dimensional indentation tests was conducted with different rock and cutter types. Acoustic emission (AE) monitoring technique was employed to capture the information of the rock damage evolution real-timely. It is found that the penetration by using the constant cross section (CCS) cutter tends to induce inconspicuous rock chips formation before the sudden occurrence of the macrocrack, but that by using the V-type cutter tends to induce gradual rock fragmentation accompanied by the multiple local rock chips formation and the sawtooth force-penetration curve. Meanwhile, rock fragmentation models for CCS and V-type cutters were compared, and the spatio-temporal evolution of AE events was quantitatively analyzed to reflect the rock damage zone development process. Results indicate that the V-type cutter has greater penetration ability and the CCS cutter can cause larger unit damage zone radius. Microscopic observation by using the scanning electron microscope (SEM) reveals that the fracture mechanism for the crushed zone of rock is mainly shear type and that for the major crack is tensile type. It does not matter with rock types or cutter types. [ABSTRACT FROM AUTHOR]