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Evaluation the Surface Settlement and Interaction Between Tunnelinline2 and Metro Station Inline1 of Mashhad Metro at Intersection Using 3-D Numerical Modeling

Ghasempour, Hamid | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43704 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Sadaghiani, Mohammad Hossein
  7. Abstract:
  8. In this study, the interaction of tunneling of line 2 of Mashhad metro and existing metro station (Shariati station) in line 1 has been investigated. To produce the stress and displacement which is caused by excavation of station, the process of station excavation has been modeled by method of cut and cover.This method is the common method for station construction at Shallow depth and is used in several cases in line 1 of Mashhad metro. The piled-raft system is used in foundation of central part of the station to reduce the settlements and the effects of interactions between the station and new tunnel. The new tunnel under the station is surrounded by two rows of lateral piles with distance of 20 cm from the Tunnel. In design of new tunnel line 2 which is excavated by EPB shield TBM, it is important to control the safety of station in vicinity of tunnelling activities of line 2. Therefore, it is necessary to understand the mechanisms of interaction between station and tunnel and surface settlements due to the construction of new tunnel. In order to study these mechanisms, the full three dimensional (3D) finite element program ABAQUS 6.10.1 is used. Mohr-colomb model is used to simulate the ground behavior. In order to investigate the factors influencing the interaction of station and new tunnels, sensitivity analysis has been done on geotechnical properties of the soil, distance between the station and new tunnel, traffic load, stiffness of tunnel lining, piles and the pressure to which tunnel face is exposed. The results show that the surface settlement and its difference due to excavation of line 2 has been reduced properly by using piled – raft system. The results also show that the interaction effects are decreased by increasing distance between the station and the tunnel. The results of sensitivity analysis on soil properties also show that improving the soil properties between the station and the tunnel can reduce the surface settlements. Also, there are very little surface settlement changes at intersection zone when the pressure on the tunnel face is changed
  9. Keywords:
  10. Metro Stations ; Ground Surface Settelment ; Three Dimensional Modeling ; Finite Element Method ; Earth Pressure Balanced (EPB)Tunneling ; Tunnel Boring Machine (TBM) ; Tunneling Induced Settlement

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