A proposed model of limit equilibrium analysis for stability assessment of underground structure in liquefied ground during earthquakes

Ju-Young Oh; Jaehwan Lee; Seokbue Chang

doi:10.9711/KTAJ.2024.26.5.435

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2024 Vol.26, Issue 5 Preview Page Next Page

Technical Paper

A proposed model of limit equilibrium analysis for stability assessment of underground structure in liquefied ground during earthquakes 지진 시 액상화된 지반 내 지중 구조물의 안정성 평가를 위한 한계평형해석 모델 제안

30 September 2024. pp. 435-448

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Abstract

Liquefaction of the ground caused by earthquakes results in significant damage to underground structures such as tunnels, pipelines, manholes, and underground tanks. The uplift of underground structures due to liquefaction has been identified as a major cause of this damage. However, current design practices have not adequately considered the upward displacement of underground structures. This paper proposes an analytical solution based on the limit equilibrium method for cut-and-cover tunnels. Using this solution, a sensitivity analysis was performed on soil cover height, liquefaction depth, ground improvement, and ledge. It was confirmed that the contribution of each factor to the safety factor can be reasonably derived through changes in the safety factor. Although there are still many assumptions and uncertainties that need to be reviewed for their appropriateness, a conservative approach appears to mitigate a significant portion of these uncertainties. This study is meaningful as a stability evaluation method considering the uplift behavior characteristics of underground structures.

Keywords

Earthquake

Liquefaction

Uplift

Underground structure

Limit equilibrium analysis

지진 시 발생하는 지반의 액상화는 터널, 관로, 맨홀, 지하 탱크 등 지중 구조물에 큰 피해를 초래한다. 이러한 액상화에 의한 피해는 지중 구조물의 부상(uplift)이 주요 원인인 것으로 나타났으며, 현재까지 설계 실무에서는 지중 구조물의 이러한 상향 변위를 충분히 고려하지 못하고 있는 실정이다. 이에 본 논문에서는 개착식 터널을 대상으로 하여 한계평형법 기반의 analytical solution을 제안하였다. 이를 활용하여 토피고, 액상화 심도, 지반개량, ledge 유무에 대한 민감도 분석을 시행하였다. 안전율 변화를 통해 안전율에 대한 각 요소들의 기여도를 합리적으로 도출할 수 있음을 확인하였다. 현재 모델 내 다수의 가정과 불명확성이 존재하며, 이에 대한 적합 여부에 대한 검토는 여전히 과제로 남아있다. 하지만, 보수적인 접근 방식을 통해 상당 부분의 불확실성이 완화된 것으로 판단되며, 지중 구조물의 uplift 거동 특성을 고려한 안정성 평가 방법이라는 점에서 의미가 있다고 사료된다.

키워드

지진

액상화

Uplift

지중 구조물

한계평형해석

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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 : 26
No :5
Pages :435-448
Received Date : 2024-07-16
Revised Date : 2024-09-20
Accepted Date : 2024-09-20
DOI :https://doi.org/10.9711/KTAJ.2024.26.5.435

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

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