한국지구과학회지 (Journal of the Korean earth science society)

  • 제38권2호
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  • Pages.161-171
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  • 2017
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  • 1225-6692(pISSN)
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  • 2287-4518(eISSN)
한국지구과학회 (The Korean Earth Science Society)
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기준관측소 방법을 이용한 댐체 기반암의 동적 지반증폭특성

The Dynamic Basement Amplification Characteristics of a Dam Site using a Reference Site Method

  • 위성훈 (한국지질자원연구원 지진연구센터) ;
  • 김준경 (세명대학교 소방방재학과) ;
  • 유성화 (한국지질자원연구원 지진연구센터)
  • Wee, Soung-Hoon (Earthquake Research Center, Korea Institute of Geoscience and Mineral Resources) ;
  • Kim, Jun-Kyoung (Department of Fire Protection Engineering, Semyung University) ;
  • Yoo, Seong-Hwa (Earthquake Research Center, Korea Institute of Geoscience and Mineral Resources)
  • 투고 : 2017.02.07
  • 심사 : 2017.04.11
  • 발행 : 2017.04.30
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초록

관측된 지반진동은 지진원, 지각감쇠 및 지반의 증폭특성 등 3가지 주요 인자로 구성되어 있고 특히 지반증폭 특성은 지진원 및 감쇠특성을 평가할 때 필요하다. 또한 지진재해도를 분석하기 위해 지반의 증폭 특성에 정보가 내진공학 뿐만 아니라 암반공학적 특성 분석에서 필수적이다. 지반의 증폭특성 분석을 위해 분석대상 관측소와 기준 관측소 지반진동의 수평/수직 비를 이용하는 방법을 적용하였다. 기존의 기준관측소의 수직성분 방법에 더하여 새로이 기준관측소의 수평성분 방법을 새로이 시도하였다. 본 연구는 예당저수지 인근에 설치한 4개의 관측소에서 관측된 6개의 가속도 지반진동을 이용하여 각 지반진동의 S파, Coda파 및 배경잡음 각각을 분석한 지반증폭 특성을 상호 비교하였다. 4개 관측소 공통적으로 S파와 Coda파를 이용한 결과는 상호 유사한 지반증폭 특성을 보였다. 다만 배경잡음은 다른 2개 지진 에너지와 비교할 때 전혀 다른 지반증폭 특성을 보였고 이는 배경잡음의 발생 원인이 관측소 마다 서로 다르기 때문으로 입증되었다. 4개 각각의 지진 관측소마다 저주파수 및 고주파수 증폭특성과 관측소 고유의 우월주파수가 서로 상이하여 관측소 고유의 증폭특성을 보여주었다. 또한 본 연구의 결과와 다른 방법의 결과와 비교하면 지반의 동적특성 및 지반분류 연구에 많은 정보를 제시할 수 있다.

Observed ground motions are composed of three factors such as, seismic source, attenuation, and site amplification effect. Among them, the site amplification characteristics should be considered significantly when estimating seismic source and attenuation characteristics with more confidence. The site effect is also necessary when estimating not only seismic hazard in seismic design engineering but also rock mechanical properties. This study uses the method of H/V spectral ratio of observed ground motion between target site and reference site called a reference site method. In addition to using the vertical Fourier spectrum of the reference site, we try out the horizontal Fourier spectrum as a new method in this study. We analyze H/V spectral ratio of six ground motions respectively, observed at four sites close to Yedang Reservoir. We then compare site amplification effects at each site using 3 kinds of seismic energies including S waves, Coda waves energy, and background noise. The results suggest that each site showed similar site amplification patterns in S waves and Coda waves energy. However, the site amplification of background noise shows much different characteristics from those of S waves and Coda wave energy, which suggests that the background noises at each site have their own developing mechanism. Each station shows its own characteristics of specific resonance frequency and site amplification properties in low, high and specific resonance frequency ranges. Comparison of the method used in this study to the others that used different methods can provide us with more information about the dynamic amplification of a site characteristics and site classification.

키워드

참고문헌

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