Comprehensive TBM type selection method for deep complex grounds and its application in Yangtze-River-to-Han-River Water Diversion Project

The Yangtze-River-to-Han-River Water Diversion Project is currently the most challenging water diversion tunnel engineering under construction in China due to its overall construction difficulty. It will employ ten super-large diameter tunnel boring machines (TBMs) and frequently encounter engineering disasters such as strong water/mud inrush, high external water pressure, strong rockburst in hard rocks, large deformation in soft rocks, high abrasive and strength rocks, harmful gases. They will severely affect the construction project and safety and thus bring great challenges to TBM type selection based on its geological adaptability. This study proposes the comprehensive TBM type selection method for deep complex grounds. First, the quantitative TBM type selection method is established based on the TBM type selection method considering the threshold values for adverse geological conditions and the TBM type selection method considering its adaptability evaluation in deep mixed grounds. Then, the comprehensive TBM type selection method is established by fully considering its adaptability to main geological condition, special geological condition and supporting system, construction period, economy, environment and safety. Finally, this method is employed for the comprehensive TBM type selection for Yangtze-River-to-Han-River Water Diversion Project tunnels. The results of this study can offer guidance and reference for TBM type selection based on its geological adaptability in deep complex grounds.