A comparative study on the stability evaluation of double deck tunnel in terms of excavation

대심도 복층터널에 대한 굴착 안정성 평가 비교 연구

  • Jang, Namju (Geotechnical Department, Sambo Engineering Co., Ltd.) ;
  • Gang, Han-gil (Geotechnical Department, Sambo Engineering Co., Ltd.) ;
  • Kim, Kihwan (Geotechnical Department, Sambo Engineering Co., Ltd.) ;
  • Choi, Chang-rim (Geotechnical Department, Sambo Engineering Co., Ltd.)
  • 장남주 (삼보기술단 지반사업부) ;
  • 강한길 (삼보기술단 지반사업부) ;
  • 김기환 (삼보기술단 지반사업부) ;
  • 최창림 (삼보기술단 지반사업부)
  • Received : 2018.12.01
  • Accepted : 2018.12.14
  • Published : 2019.01.31


It is necessary to construct underground in the metropolis. Road traffic has reached saturation point. The city has several underground road construction projects. In abroad, double deck tunnels are planned and constructed. It is attained a high level of underground development technology. In case the double deck tunnel (2 lane) is planed instead of the bidirectional tunnel (2 lane), excavation area is similar. But tunnel width is decreased. The reduced width can cut cost for the tunnel reinforcement. This study evaluates the stability of excavation on double deck tunnel. By the assessment of the strength-stress ratio and strength reduction method, quantitative analysis is conducted between double deck tunnel and the bidirectional tunnel.

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Fig. 1. Calculation of local factor of safety (You et al., 2000)

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Fig. 2. Shear strength and trial shear strength (Park and You, 1998)

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Fig. 3. Road alignment plan in branch section (Seoul ○○○ tunnel)

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Fig. 4. Road alignment plan in branch section– reduced speed section (up), raised speed section (down)

Table 1. Tunnel in branch section (Seoul ○○○ tunnel)

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Table 2. Double deck tunnel in branch section

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Table 3. Analysis condition

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Table 4. Properties of rock mass

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Table 5. Load relaxation factors

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Table 6. Rock support pattern

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Table 7. Plastic failure zone in single tunnel

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Table 8. Plastic failure zone in double deck tunnel

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Table 9. Local factor of safety in single tunnel and double deck tunnel

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Table 10. Global factor of safety in single tunnel and double deck tunnel

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Grant : 대심도 복층터널 설계기술 및 시공기술개발

Supported by : 국토교통과학기술진흥원


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