Seismic Analysis Of The Secondary Lining Of The Yue Longmen Tunnel Portal

In recent years, earthquake disaster frequently occurred in whole world which brought great damage to the safety of life and property for people. The tunnel structure is one of the important structures of the underground transportation system and the hinge of transportation system. The destruction of the tunnel structure, not only caused a huge direct economic loss, but also hampered relief work and reconstruction task. The tunnel portal is extremely vulnerable to structure damage in terms of the whole tunnel. Therefore it is necessary to investigate the anti-seismic research on the secondary lining of the lunnel portal.Referring related criterion, it is clearly that the lining design of the shallow buried tunnel portal must be strengthened, which means earthquake fortification. However, how to design the earthquake fortification is not specified in this paper, because the specific design on how to strengthen is based on the experience. Whether the tunnel lining structure is keep health under the fortification intensity and earthquake load has a great deal of uncertainty. Whether increasing the concrete lining stiffness can improve the earthquake-resistance performance need to be further studied.Based on the above problems, this paper analyzes the dynamic responses of the secondary lining of the Yue Longmen tunnel portal, including the maximum displacement, the acceleration, the stress and internal force, and checks the compressive strength and tensile strength under three-dimensional (3-D) ground motion and numerical modeling.The differences of concrete lining stiffness are compared to the earthquake-resistance performance.The results show that:(1) The arch spring, where the maximum value of the stress force, the shear force and the bending moment are obtained, generates the region of stress concentration under 3-D ground motion. Measures must be taken to reduce the arch spring force in design.(2) The secondary lining of the Yue Longmen tunnel portal can satisfy the standard request both in the compressive and tensile properties under 3-D ground motion. The compressive and tensile safety factors are also greater than the norm design value. The earthquake fortification of the secondary lining of the Yue Longmen tunnel portal is reasonable.(3)Increasing the concrete lining stiffness can not obviously improve the earthquake-resistance performance.