Abstract:
Compared with the conventional composite lining, the multi-layer lining loaded by large water pressure can reserve one more waterproof board and guarantee its construction quality when tunnel passes through karstprone section. This paper sets forth an analysis model of the multi-layer lining and comes to the following conclusions through a case study: when stiffness coefficient of the compression-only spring between inner lining and outer lining increases, bending moments of the inner and outer lining are basically unchanged and axial force of outer lining decreases and eccentricity increases while axial force of inner lining increases and eccentricity decreases. When water pressure load increases, the state of lining vault transfers from large eccentric compression into small eccentric compression state and then approaches compressive ultimate load bearing state and the safety factors increase at first and then decreases; state of haunch and side wall gradually approaches the ultimate load bearing state and the safety factors gradually reduce; the states of arch foot and inverted arch transfer from small eccentric compression to large eccentric compression and the safety factors gradually reduce.