Research and Application of Key Construction Technologies for TBM-driven Tunnels under Extreme Complex Geological Conditions
(1. China Railway Tunnel Group Co., Ltd.，Guangzhou 511458 ; 2. State Key Laboratory of Shield Machine and Boring Technology,Zhengzhou 450001; 3. China Railway Tunnel Stock Co., Ltd., Zhengzhou 450001)
Abstract：
With successive construction commencement of the Gaoligongshan Tunnel of the Dali-Ruili Railway, the Qinling Tunnel of the Hanjiang-to-Weihe Water Diversion Project, and the Xianglushan Tunnel of the Central Yunnan Water Diversion Project, various TBM construction problems have become increasingly prominent, such as TBM jamming caused by water-rich, broken and extremely soft strata, and rockburst caused by extremely hard rock strata with high in-situ stress. Firstly, this paper compares and elaborates on the typical adverse geological conditions such as broken and soft rock, and extremely hard granite commonly encountered during the construction of TBM tunnels in China and their impacts on TBM boring. On the basis of summarizing and analyzing the tunnel collapse and TBM jamming cases, and their influencing factors during the construction of various projects such as the Liaoning northwest water supply project, the songhua river water diversion project, and the tao river water supply project, this paper conducts a systematic study on the key TBM boring technologies under extreme complex geological conditions, and the results show that: (1) the advance geological prediction technology is an important tool for TBM construction to cope with extreme complex geological conditions, but presently, it is not yet possible to accurately quantify and predict the geological conditions in the medium and long distance ahead of the tunnel face.Based on the analysis results of micro-seismic monitoring, corresponding countermeasures may be taken according to potential different rockburst levels such as minor, moderate and intense rockburst levels. For different soft and broken strata such as developed joints, carbonaceous slates, fault and broken zones, etc., targeted measures should be taken to prevent TBM jamming, while a suitable TBM machine release scheme can be chosen according to the length of the poor geological section. (2) Abnormal fluctuations of TBM boring parameters such as thrust, advancing speed, cutterhead rotation speed and torque are important indicators to characterize the geological conditions in front of the tunnel face. Before the TBM excavation, appropriate TBM boring parameters should be selected respectively according to the pre-estimated surrounding rock conditions such as full-face hard rocks or soft and fractured rocks. During the TBM boring process, the predicted geological conditions should be corrected timely, and corresponding control measures should be adjusted based on the abnormal changes of the boring parameters, thus ensuring that the TBM is in the best boring condition. (3) In view of the fact that it is difficult for the existing TBMs to adapt to the existing geological conditions, this paper carries out an analysis and discussion on the TBM modification technologies with the tunnels in the Tao river diversion and water supply project, the Hongyan river-to-shitou river water diversion project and the Hanjiang-to-weihe water diversion project as examples. Finally, it discusses the new problems that could arise in TBM tunnel construction under extreme complex geological conditions and future prospects of corresponding countermeasures.
FENG Huanhuan1,
2 HONG Kairong1,
2 YANG Yandong2 YANG Luwei1 SI Jingzhao1 YOU Jinhu3
.Research and Application of Key Construction Technologies for TBM-driven Tunnels under Extreme Complex Geological Conditions[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(1): 42-54
2022, Vol. 59 