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Investigation on the Effect of Earthquake loads on Segmental Lining in Tunnel

Khaleghi, Hooman | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 39415 (53)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Sadaghiani, Mohammad Hossein
  7. Abstract:
  8. Recently, considerable efforts have been devoted to evaluation of seismic dynamic response of a circular tunnel. Conventional approaches have considered integral liners embedded in an elastic medium. In this study, we model a circular tunnel driven by TMB in homogeneous soil. Tunnel lining with 6 pieces of segments is analyzed by software in three dimensions. The results demonstrate that the stiffness difference between the segment and joints can enhance the internal forces of the segment significantly, which is crucial for the design of segments. The design of tunnel segment joints and joints between tunnels and portal structures are investigated by comparing with different parameters of soil and concrete. The study showed that as the number of segments increases the bending moment and thrust decrease. However, beyond a critical number of joints, the increase of number of joints has little influence on the values of stresses induced in the lining. It has been also shown that the effects of joint orientation is significant in determining the stress level in the lining for cases where the in-situ stress is higher or lesser than unity. A simple design methodology to determine the stresses induced in jointed lining without incorporating the joints in the analysis has been proposed. The purpose of this thesis is to present the Soil-ground-Structure Interaction for tunnels analysis and behavior of segmental lining performed for different dynamic load condition. Segmental linings are primarily used in tunnel that excavated by Tunnel Boring Machine (TBM) in homogenous medium. In this study, we modeled a circular tunnel driven by TMB in homogeneous soil and the tunnel was modeled with 6 pieces of segment at earthquake. Three records of Tabas Earthquake (1978, Iran) at each direction (X, Y and Z) is selected for analysis the system of soil-tunnel. The Tabas Earthquake was capable of generating a peak horizontal (X-direction) ground acceleration of 0.82g and vertical (Y-direction) ground accelerations in excess of 0.6g and Z-direction ground acceleration of 0.84g, the duration of the seismic event was exceeded 30 seconds. Response compatible ground motion time histories were developed along the tunnel alignment. The objectives of the analysis are to estimate the responses of tunnels lining behavior due to seismic excitations. Time domain response of a circular tunnel with prefabricated segmental lining subjected to seismic waves is investigated and the results and comparison about stresses and displacements of tunnel and interaction between two rings at earthquake is demonstrated
  9. Keywords:
  10. Soil-Structure Interaction ; Finite Element Method ; Soil ; Tunnels

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