Assessment of tunnel stability according to height of embankment by numerical analysis

Kang-Hyun Lee; Sangrae Lee; Nag-Young Kim

doi:10.9711/KTAJ.2021.23.1.037

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2021 Vol.23, Issue 1 Preview Page Next Page

Research Paper

Assessment of tunnel stability according to height of embankment by numerical analysis 수치해석을 통한 성토 높이에 따른 터널 안정성 평가 연구

31 January 2021. pp. 37-45

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Abstract

The construction of the tunnel portal should be careful because cover depth is shallow and it is difficult to exhibit the arching effect. Tunnel stability may be reduced with additional embankment above the portal of tunnel. In this study, in order to examine the stability of the tunnel according to additional embankment above the portal of tunnel, numerical analysis was performed while changing the ground conditions and height of embankment. As a result of the numerical analysis, it was found that the allowable flexural compressive stress of shotcrete and allowable axial force of rockbolts were exceeded when the height of additional embankment was 12 m in rock mass rating V. When considering the displacement, the range of the plastic region and the behavior of the support materials, the tunnel stability seems to be greatly reduced if the height of additional embankment above the portal of tunnel exceeds 10 m.

Keywords

Tunnel

Stability

Cover depth

Height of embankment

터널의 갱구부는 토피가 얕고 지반의 아칭효과가 발휘되기 어렵기 때문에 터널 시공 시 주의가 필요한 구간이다. 공용 중인 터널 갱구부 상부에 추가적인 성토가 이루어진다면 터널 안정성을 크게 저해할 수 있다. 따라서 본 연구에서는 터널 상부의 추가 성토에 따른 터널 안정성을 검토하고자 지반조건별로 성토 높이에 따른 수치해석을 수행하였다. 해석 결과 5등급 암반에서 성토 높이가 12 m 이상인 경우에는 숏크리트의 허용 휨압축응력, 록볼트의 허용 축력을 초과하는 것으로 나타났다. 발생되는 변위와 소성영역의 범위, 지보재의 상태를 종합적으로 고려할 때 터널 갱구부 상부에 추가 성토되는 높이가 10 m를 초과하는 경우에는 터널 안정성이 크게 저해되는 것으로 판단된다.

키워드

터널

안정성

토피고

성토 높이

References

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Information

Publisher :Korean Tunneling and Underground Space Association
Publisher(Ko) :한국터널지하공간학회
Journal Title :Journal of Korean Tunnelling and Underground Space Association
Journal Title(Ko) :한국터널지하공간학회 논문집
Volume : 23
No :1
Pages :37-45
Received Date : 2020-12-22
Revised Date : 2021-01-15
Accepted Date : 2021-01-15
DOI :https://doi.org/10.9711/KTAJ.2021.23.1.037

Journal of Korean Tunnelling and Underground Space Association ISSN:2233-8292(Print) 2287-4747(Online) 한국터널지하공간학회 논문집

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