Abstract:

At present, the classification of the surrounding rocks based on the mining method is mainly adopted for the design and construction of TBM tunnels. Due to the great difference between the TBM method and the mining method, however, the classification of the surrounding rocks based on the mining method is not suitable for the construction of TBM tunnels. In this study, the surrounding rock classification and supporting systems of the TBM tunnels of the Water Supply Phase Ⅱ Project in North Xinjiang in China are studied: the basic quality index of the surrounding rocks (BQ), the saturated uniaxial compressive strength of the rock (〖WT５ＢＸ〗R〖ＷＴ〗〖WT５《TNR》〗c), the intactness factor of the rock mass (〖ＷＴ５ＢＸ〗K〖ＷＴ〗〖WT５《TNR》〗V), and Cerchar abrasiveness index (CAI) are taken as the main indices to evaluate the properties of the surrounding rocks of the TBM tunnels, and the statistics of nearly 3 000 sets of lithologic index data including BQ, 〖WT５ＢＸ〗R〖ＷＴ〗〖WT５《TNR》〗c, and 〖ＷＴ５ＢＸ〗K〖ＷＴ〗〖WT５《TNR》〗V in the tunneling of 18 TBMs are collected, with comprehensive consideration of the stability and boreability of the surrounding rocks; the rules of the variation of the net progress rates PR and the safety factors 〖ＷＴ５ＢＸ〗F〖ＷＴ〗〖WT５《TNR》〗S along with each lithologic index are analyzed, and the surrounding rocks of the TBM tunnels are classified in to Class Ⅰ, Class Ⅱ, Class Ⅲ, Class Ⅳ, and Class Ⅴ and are further classified in to ten subclasses; on this basis, the tunneling features of open TBMs are analyzed, the stability of the surrounding rocks of each class under different supporting parameters is analyzed by means of numerical simulation, the supporting systems and supporting parameters applicable to the hydraulic tunnels with different classes of surrounding rocks in North Xinjiang are proposed, and a total of seven sets of design drawings for the supporting systems are formed; the surrounding rock classification and the supporting systems proposed herein are verified in the actual field works, and the field monitoring data show that the surrounding rock classification and the supporting systems proposed for the TBM tunnels have high applicability.

Key words: TBM tunnel, surrounding rock classification, large deformation, rockburst, supporting system, supporting parameters