The Effect of Reverse Slip Faulting on Segmental Tunnels Dug in Soil in Flac 3D Software

Document Type : Original Article

Authors

1 civil engineering student, structural major, faculty of engineering and Passive Defense, Imam Hossein University (AS)

2 Director of the Center for Basic Science and Technology of Khatam Al-Anbia Construction Research Institute and Assistant Professor of Civil Engineering, Faculty of Passive Defense Imam Hossein University

Abstract

Today, tunnels are one of the main vital arteries for a city, which are developing significantly. The development of today's societies has caused the need for tunnels in various sectors, including urban public transportation, intercity transportation, and water and sewage collection and transmission networks, etc. It goes without saying that for underground structures such as tunnels, the existence of faults and consequently earthquakes are serious threats among natural hazards. Although tunnels should not be located near active faults, sometimes passing through them is unavoidable. Sometimes, after the construction of the tunnel, the existence of the fault is known. In such cases, the deformation caused by the fault is considered a big concern and has a significant effect on the behavior of the tunnels. Meanwhile, due to the fact that most urban shallow tunnels are built in loose ground, the necessity of studying the behavior of tunnels and ensuring the safety of these structures against failure is of great importance. The advantage of numerical methods, in this research, the effect of different parameters such as the thickness of the piece, the depth of the tunnel placement and the fault angle on the behavior of piece tunnels has been investigated using FLAC 3D software. The main goal of the research was to know the possible failure mechanism of segmental tunnels due to faulting. In this research, 24 numerical models were built to understand the behavior of segmental tunnels under the effect of reverse faulting. The validation of this numerical modeling is with the physical model of Kiani et al. The ways to improve the performance of segmental tunnels when faced with reverse fault movement is to increase the rigidity of the tunnel. In this research, the effect of the depth of the tunnel placement due to the reverse fault was also investigated. It was observed that increasing the depth of the tunnel placement when facing reverse faulting leads to a decrease in the deformation of the tunnel diameter. Also, the effect of changing the fault angle for the tunnel was investigated. Increasing the angle of the fault causes the change of places created on the ground surface and the displacement of the tunnel roof to decrease.

Keywords

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References

[1]  M. Kiani, et al., "Experimental evaluation of vulnerability for urban segmental tunnels subjected to normal surface faulting." Soil Dynamics and Earthquake Engineering, vol. 89, pp. 28-37, 2016.
[2]   M. Zaheri, et al., "Performance of segmental and shotcrete linings in shallow tunnels crossing a transverse strike-slip faulting," Transportation Geotechnics, vol. 23,: p. 100333, 2020.
 [3]  N.-A.Do, et al., "2D numerical    investigation of segmental tunnel lining behavior," Tunnelling and Underground Space Technology, vol. 37,  pp. 115-127, 2013.
 [4] B. Das and K. Sobhan, "Principles of Geotechnical Engineering, CENGAGE  Learning, Stamford, USA," 2013.
  [5] M. H. Baziar, et al., "Centrifugemodeling of interaction between reverse faulting and tunnel," Soil Dynamics and Earthquake Engineering, vol. 65, pp. 151-164, 2014.
   [6] M.-L. Lin, et al., "The deformation of overburden soil induced by thrust faulting and its impact on underground tunnels," Engineering Geology, vol. 92(3-4), pp. 110-132, 2007.
   [7] Z. Zhang, et al., "Influence of fault on the surrounding rock stability of a tunnel: Location and thickness," Tunnelling and Underground Space Technology, vol. 61, pp. 1-11, 2017.

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History

  • Receive Date: 12 August 2022
  • Revise Date: 31 October 2022
  • Accept Date: 05 February 2023

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