Dynamic Response of Underground Single and Twin Tunnels to Earthquakes
Date Issued
2015
Date
2015
Author(s)
Lin, Szu-Yun
Abstract
In densely populated metropolitans, it is beneficial and desirable to construct the transportation system and other networks of lifelines underground, such as subways, water, gas, and electricity pipes. During a devastating earthquake, such vital infrastructure may be damaged and become dysfunctional, resulting in the loss and damage of lives and property. As part of the effort to address the above issue, the purpose of this thesis is to study the seismic responses of underground tunnels, including twin-tunnels, and the effect of tunnels on the seismic responses of the ground and tunnels. In this thesis, the finite/infinite element approach proposed by Yang et al. (1996) is adopted to simulate the two-dimensional response of an elastic half space containing cylindrical tunnels subjected to vertically incident body waves. In addition, to deal with the scattering of seismic waves, the procedure of simulating earthquake excitations proposed by Zhao and Valliappan (1993) is adopted. Then a reasonable procedure will be presented for imposing the excitations based on the free-field motions recorded for earthquakes. Particularly, the free-field seismic motion recorded for the 921 Chi-Chi Earthquake will be adopted in the seismic responses of the underground tunnels. Furthermore, a parametric study is performed to investigate the effects of tunnel depth, spacing between the twin-tunnels, stiffness of the tunnel lining, and Young’s modulus of the soil on the ground and tunnel responses. In the end, the effect of different soil compositions of the half-space is discussed. The results from this study indicate that the seismic responses of the tunnels and the ground will be affected significantly by the tunnel lining, stiffness of the soil, and different soil compositions of ground. Even though the tunnel depth and spacing between the twin-tunnels are important parameters with respect to the seismic responses of the tunnels, they have less effect on the ground responses.
Subjects
2D finite/infinite element method
soil-structure interaction
half-space
tunnel
twin-tunnels
interaction behaviors
seismic response
SDGs
Type
thesis