Journal of Korean Society of Disaster and Security (한국방재안전학회논문집)

Korean Society of Disaster & Security (한국방재안전학회)
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Seismic Risk Assessment on Buried Electric Power Tunnels with the Use of Liquefaction Hazard Map in Metropolitan Areas

액상화 재해지도를 이용한 수도권 전력구 매설지반의 지진시 위험도 평가

  • Baek, Woohyun (Department of civil engineering, Seoul National University of Science and Technology) ;
  • Choi, Jaesoon (Department of civil and architecture engineering, Seokyeong University)
  • 백우현 (서울과학기술대학교 토목공학과) ;
  • 최재순 (서경대학교 토목건축공학과)
  • Received : 2019.03.04
  • Accepted : 2019.03.25
  • Published : 2019.03.31
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Abstract

In this study, the seismic risk has been evaluated by setting the bedrock acceleration to 0.154g which, was taking into consideration that the earthquake return period for the buried electric power tunnels in the metropolitan area to be 1,000 years. In this case, the risk assessment during the earthquake was carried out in three stages. In the first stage, the site classification was performed based on the site investigation data of the target area. Then, the LPI(Liquefaction Potential Index) was applied using the site amplification factor. After, candidates were selected using a hazard map. In the second stage, risk assessment analysis of seismic response are evaluated thoroughly after the recalculation of the LPI based on the site characteristics from the boring logs around the electric power area that are highly probable to be liquefied in the first stage. The third Stage visited the electric power tunnels that are highly probable of liquefaction in the second stage to compensate for the limitations based on the borehole data. At this time, the risk of liquefaction was finally evaluated based off of the reinforcement method used at the time of construction, the application of seismic design, and the condition of the site.

본 연구는 수도권 지역의 전력구 매설지반을 대상으로 지진 재현주기 1,000년을 고려한 최대기반암가속도 0.154g로 설정하여 지진시 위험을 평가하였다. 이때, 지진시 위험도 평가는 총 3단계로 진행하였으며 1단계는 대상지역의 지반조사 정보를 기초로 지반분류를 우선 실시한 후, 액상화 발생가능성을 파악할 수 있는 Macro영역 기법인 지반증폭계수를 이용한 액상화 발생가능지수(LPI, Liquefaction Potential Index) 재해지도를 이용하여 후보지를 선정한다. 2단계 위험도 평가는 1단계 평가에서 액상화 발생가능성이 매우 높게 판정된 전력구 주변의 시추주상도를 바탕으로 부지특성을 반영한 지진응답해석을 수행하고 이를 토대로 액상화 발생가능성 지수를 재산정하여 지진시 액상화 위험도를 상세평가 하였다. 3단계는 시추공자료를 기반으로 하는 한계성을 보완하기 위하여 2단계에서 액상화 발생가능성이 높게 평가된 대상 전력구의 현장조사를 실시하여 건설시 보강공법적용, 내진설계적용 및 현장상태 등을 고려하여 최종적으로 액상화 위험도를 평가하였다.

Keywords

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Fig. 1. Study area & Location of electric power tunnel

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Fig. 2. Framework for the study

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Fig. 3. Input earthquake motions in site response analyses

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Fig. 4. Preliminary assessment of study area using LPI hazard map

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Fig. 5. Zoom-in at a dangerous area in seoul

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Fig. 6. The results of site response analyse

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Fig. 6. The results of site response analyse (continued)

Table 1. Level of liquefaction damage by LPI (Iwasaki et al., 1982)

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Table 2. Amplification coefficient according to soil type (EESK, 1997)

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Table 3. Field survey standard criteria

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Table 4. LPI from response analyses

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