Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Estimation of Variability of Soil Properties and Its Application to Geotechnical Engineering Design

지반정수의 변동성 추정 및 결과의 활용

  • Kim, Dong-Hee (School of Civil, Environmental and Architectural Engrg, Korea Univ.) ;
  • Kim, Min-Tae (School of Civil, Environmental and Architectural Engrg, Korea Univ.) ;
  • Lee, Chang-Ho (School of Civil and Environmental Engrg., Georgia Institute of Technology) ;
  • Lee, Woo-Jin (School of Civil, Environmental and Architectural Engrg, Korea Univ.)
  • 김동휘 (고려대학교 건축.사회환경공학부) ;
  • 김민태 (고려대학교 건축.사회환경공학부) ;
  • 이창호 (조지아공대 토목환경공학과) ;
  • 이우진 (고려대학교 건축.사회환경공학부)
  • Received : 2010.06.07
  • Accepted : 2010.10.25
  • Published : 2010.12.31
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Abstract

The reliable evaluation of the coefficient of variation (COV) of soil properties is required for the determination of adequate design values and the application of a probabilistic method for the design of geotechnical structures. In this paper, the applicability of methods for estimating the standard deviation, such as the. Three-Sigma Rule and a statistical method, is evaluated by using site investigation data of the Songdo area. It is found that the Three-Sigma Rule provides similar results to those of a statistical method when using $N_{\sigma}$=6 for the property with small variability and $N_{\sigma}$=4.2~5.3 for the property with large variability. It is also observed that, for the undrained shear strength that has an increasing trend with depth, a $N_{\sigma}$ value of 4 is adequate for the evaluation of the variability by the Three-Sigma Rule. The COVs of soil properties determined in this paper could be used in the estimation of the confidence interval and characteristic values of soil properties.

설계지반정수의 합리적인 결정과 확률론적 방법에 의한 지반구조물의 설계를 위해서는 지반정수의 변동계수에 대한 신뢰성 있는 추정이 필요하다. 본 논문에서는 인천 송도지역의 지반조사자료를 이용하여 Three-Sigma Rule 및 통계적인 방법과 같은 표준편차 추정방법의 적용성을 평가해 보았다. 무작위성을 보이는 지반 물성값 중, 변동성이 작은 ${\gamma}_t$, ${\gamma}_b$, $e_0$는 $N_o=6$을, 상대적으로 변동성이 큰 $C_{\alpha}/C_c$, $C_c(1+e_0)$, $c_v$, $k_v$의 경우 $N_{\sigma}$=4.2~5.3을 사용하여 Three-Sigma Rule을 적용하면 통계학적 방법과 유사한 결과를 얻는 것이 관찰되었다. 또한 깊이에 따라 경향성을 보이는 비배수전 단강도는 약 40%의 변동계수를 보이는 것으로 관찰되었으며 $N_{\sigma}$=4를 사용하면 Three-Sigma Rule로 얻는 것으로 나타났다. 본 논문에서 추정한 변동계수를 이용하여 지반정수의 신뢰구간, 특성값을 결정할 수 있었다.

Keywords

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