Journal of the Korean GEO-environmental Society (한국지반환경공학회 논문집)

Korean Geo-Environmental Society (한국지반환경공학회)
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Soil Depth Information DB Construction Methods for Liquefaction Assessment

액상화 평가를 위한 지층심도DB 구축 방안

  • Gang, ByeongJu (Department of Civil & Environmental Engineering, Dankook University) ;
  • Hwang, Bumsik (Department of Civil & Environmental Engineering, Dankook University) ;
  • Kim, Hansam (Earthquake Reasearch Center, Korea Institute of Geoscience and Mineral Resources) ;
  • Cho, Wanjei (Department of Civil & Environmental Engineering, Dankook University)
  • Received : 2019.01.05
  • Accepted : 2019.01.24
  • Published : 2019.03.01
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Abstract

The liquefaction is a phenomenon that the effective stress becomes zero due to the rapidly accumulated excess pore water pressure when a strong load acts on the ground for a short period of time, such as an earthquake or pile driving, resulting in the loss of the shear strength of the ground. Since the Geongju and Pohang earthquake, liquefaction brought increasing domestic attention. This liquefaction can be assessed mainly through the semi-empirical procedures proposed by Seed and Idriss (1982) and the liquefaction risk based on the penetration resistance obtained from borehole DB and SPT. However, the geotechnical information data obtained by the in-situ tests or boring information fundamentally have an issue of the representative of the target area. Therefore, this study sought to construct a ground information database by classifying and reviewing the ground information required for liquefaction assessment, and tried to solve the representative problem of the soil layer that is subject to liquefaction evaluation by performing spatial interpolation using GIS.

액상화란 느슨한 사질토 지반에서 지진과 같은 큰 진동하중이 발생하여 과잉간극수압이 급격히 증가해 전단강도를 상실하는 현상으로 국내 포항에서 발생한 액상화 현상과 더불어 그 관심이 증가하고 있는 추세이다. 이러한 액상화 평가는 주로 Seed and Idriss(1982)가 제시한 반경험적 방법을 통해 수행할 수 있으며 시추공 DB와 SPT에서 얻어진 관입저항력을 기초로 액상화 위험을 평가할 수 있지만 획득된 시추공 DB는 일정 구역을 대표하지 못하는 문제를 내재하고 있다. 따라서 본 연구는 액상화 평가의 필요한 지반정보를 분류 및 검토하여 지반정보의 DB구축방안을 모색하고 지리정보시스템(GIS)을 활용하여 공간보간을 수행해 액상화 평가 대상이 되는 지층의 대표성 문제를 해소하고자 하였다. 액상화 발생이 예상되는 지층의 두께를 정의하는 방안에 따라 세 가지 지층심도DB구축 방안을 제시하였고 교차검증을 통해 제시한 구축방안의 정밀도를 비교, 분석하여 액상화 평가에 적합한 지층심도DB구축 방안을 제시하였다.

Keywords

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Fig. 1. Boreholes location in Incheon’s harbor (Area 1)

HJHGC7_2019_v20n3_39_f0002.png 이미지

Fig. 2. Boreholes location in reclamed land of Songdo (Area 2)

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Fig. 3. Boreholes location in Saemangeum (Area 3)

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Fig. 5. Correlation between measured value and predicted value in Area 1

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Fig. 6. Correlation between measured value and predicted value in Area 2

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Fig. 7. Correlation between measured value and predicted value in Area 3

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Fig. 8. Average of RMSE with regard to interpolation method in Area 1,2 and 3

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Fig. 4. Results of spatial interpolation in Target areas areas

Table 1. Cases where the liquefaction assessment can be skipped under current design provision

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Table 2. Geotechnical information required for the liquefaction assessment

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Table 3. Summary of soil properties for simplified procedure

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Table 4. Summary of target area

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Table 5. Summary of RMSE

HJHGC7_2019_v20n3_39_t0005.png 이미지

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