A Lining Design Method Consistent with NATM for Deep Shaft
Xiaonan He, Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mine， University of Science & Technology Beijing; Hongzhen Liang, China Coal Construction Group Limited Corporation; Xiaomin Zhou, University of Science and Technology Beijing; Yan Xu, Civil engineering Department, University of Science and Technology Beijing
With the increase of shaft excavation depth, the thickness of the shaft lining increases sharply. It is difficult to reduce thickness of lining effectively by improving high-strength concrete performance. The concept of the New Austrian Tunneling Method (NATM) is that surrounding rock plays a certain role in tunnel support. The solution should be to find the correct relationship between shaft lining thickness and rock strength, which is related with the interaction between the surrounding rock and concrete lining. The plane strain mechanics model is introduced to calculate lining thickness. Shaft lining design of Cixi Colliery in China is completed with the mechanics-based method proposed in this study. The lining design is verified through numerical simulation and field monitoring. The simulation results show that the maximum mises stress is located at the inner edge of the shaft lining. The increase of lining thickness can not effectively reduce concrete grade. The monitoring results indicates that lining design, thickness of 900mm with C60 concrete, is safe and reliable in the shaft over 1000 meters. This analytical design method can well be referenced in similar deep shaft project.
Deep shaft, mechanics model, shaft lining thickness, engineering practice