Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
권호 표지
DOI QR코드

DOI QR Code

Evaluation of Estimation and Variability of Fines Content in Pohang for CPT-based Liquefaction Assessment

CPT 기반 액상화 평가를 위한 포항지역 세립분 함량 예측 및 변동성 평가

  • Bong, Tae-Ho (Institute of Construction and Environmental Engrg., Seoul National Univ.) ;
  • Kim, Sung-Ryul (Dept. of Civil and Environmental Engrg., Seoul National Univ.) ;
  • Yoo, Byeong-Soo (Dept. of Civil and Environmental Engrg., Seoul National Univ.)
  • 봉태호 (서울대학교 건설환경종합연구소) ;
  • 김성렬 (서울대학교 건설환경공학부) ;
  • 유병수 (서울대학교 건설환경공학부)
  • Received : 2019.02.28
  • Accepted : 2019.03.19
  • Published : 2019.03.31
Download PDF
⟨ Previous Next ⟩

Abstract

Recently, the use of CPT-based liquefaction assessment method has increased by providing more accurate results than other field tests. In CPT-based liquefaction evaluation, various soil properties are predicted and they are used for liquefaction potential assessment. In particular, fines content is one of the important input parameters in CPT-based liquefaction assessment, so it is very important to use correct prediction model and to make quantitative evaluation of estimating variability of fines content. In this study, the error evaluation of existing models for prediction of fines content through CPT was performed, and the most suitable model was selected for Pohang area, where the liquefaction phenomenon was observed in the 2017. In addition, the inherent variability of soil was analyzed, and the estimating variability of fines content was evaluated quantitatively considering the inherent variability of soil, measurement error of CPT and transformation uncertainty of selected model.

최근 다른 현장시험에 비하여 비교적 정확성이 높은 CPT 기반 액상화 평가법의 사용이 증가하고 있다. CPT 기반 액상화 평가는 다양한 흙의 특성을 예측하고 이를 액상화 평가에 활용할 수 있다. 특히, 세립분 함량은 CPT 기반 액상화 평가에서 중요한 입력 변수 중 하나로 이에 대한 정확한 예측식의 사용 및 예측 변동성을 정량적으로 파악하는 것은 매우 중요하다. 본 연구에서는 2017년 포항지진 시 액상화 현상이 관측된 지점에서 수행된 CPT 자료를 이용하여 기존 세립분 함량 예측식들의 오차를 분석하고 포항지역에 적합한 세립분 함량 예측식을 선정하였다. 또한, 지반의 고유한 변동성을 분석하고 CPT의 측정오차, 선정된 예측식에 대한 변환 불확실성을 고려한 세립분 함량의 예측 변동성을 정량적으로 평가하였다.

Keywords

GJBGC4_2019_v35n3_37_f0001.png 이미지

Fig. 1. Correlations between soil behaviour type index and fines content

GJBGC4_2019_v35n3_37_f0003.png 이미지

Fig. 3. Study area with five site investigation locations

GJBGC4_2019_v35n3_37_f0004.png 이미지

Fig. 4. Correlations between soil behaviour type index and fines content

GJBGC4_2019_v35n3_37_f0005.png 이미지

Fig. 5. Trend removal of Ic and inherent variability (CH-1)

GJBGC4_2019_v35n3_37_f0006.png 이미지

Fig. 6. Comparison of measured and estimated fines content and confidence interval for ±St. Dev.

GJBGC4_2019_v35n3_37_f0007.png 이미지

Fig. 2. Uncertainty in soil property estimates (Kulhawy, 1992)

Table 1. Boundaries of soil behaviour type

GJBGC4_2019_v35n3_37_t0001.png 이미지

Table 2. Summary of laboratory test and CPT results

GJBGC4_2019_v35n3_37_t0002.png 이미지

Table 3. Error evaluation of prediction models for fines content prediction

GJBGC4_2019_v35n3_37_t0003.png 이미지

Table 4. Statistical properties of standard deviation for fines content prediction

GJBGC4_2019_v35n3_37_t0004.png 이미지

References

  1. Baecher, G. B. (1986), "Geotechnical error analysis", Transportation Research Record No. 1105, Structure Foundations, pp.23-31.
  2. Bandini, P. and Sathiskumar, S. (2009), "Effects of Silt Content and Void Ratio on the Saturated Hydraulic Conductivity and Compressibility of Sand-silt Mixtures", J. Geotech. Geoenviron. Eng., Vol.135, No.12, pp.1976-1980. https://doi.org/10.1061/(ASCE)GT.1943-5606.0000177
  3. Bong, T. H. and Kim, B. I. (2017), "Probabilistic Analysis of Liquefaction Induced Settlement Considering the Spatial Variability of Soils", J. of the Korean Geotechnical Society, Vol.33, No.5, pp.25-35. https://doi.org/10.7843/kgs.2017.33.5.25
  4. Boulanger, R. W. and Idriss, I. M. (2015), "CPT-Based Liquefaction Triggering Procedure", J. Geotech. Geoenviron. Eng., Vol.142, No.2, pp.1-11.
  5. Christian, J. T. (2004), "Geotechnical Engineering Reliability: How well do we know what we are doing?", J. Geotech. Geoenviron. Eng., Vol.130, No.10, pp.985-1003. https://doi.org/10.1061/(ASCE)1090-0241(2004)130:10(985)
  6. Cox, B. R., et al. (2013), "Liquefaction at Strong Motion Stations and in Urayasu City during the 2011 Tohoku-Oki Earthquake", Earthquake Spectra, Vol.29, No.S1, pp.S55-S80. https://doi.org/10.1193/1.4000110
  7. DeGroot, D. J. and Baecher, G. B. (1993), "Estimating Autoconvariance of In-situ Soil Properties", J. Geotech. Geoenviron. Eng., Vol.119, No.1, pp.147-166. https://doi.org/10.1061/(ASCE)0733-9410(1993)119:1(147)
  8. Filippas, O. B., Kulhawy, F. H., and Grigoriu, M. D. (1988), "Reliability based foundation design for transmission line structures: uncertainties in soil property measurement", Electric Power Research Institute, Report EL-5507(3), Palo Alto, CA.
  9. Green, R. A., Cubrinovski, M., Cox, B., Wood, C., and Wotherspoon, L. (2014), "Select Liquefaction Case Histories from the 2010-2011 Canterbury Earthquake Sequence", Earthquake Spectra, Vol.30, No.1, pp.131-153. https://doi.org/10.1193/030713EQS066M
  10. Idriss, I. M. and Boulanger, R. W. (2008), "Soil liquefaction during earthquakes", Monograph MNO-12, Earthquake Engineering Research Institute, Oakland, CA.
  11. Kim, J. K., Yoon, W. S., Park, S. J., and Chae, Y. S. (2008), "Effect of Liquefaction Resistence of Fine-Grained Soils on the Reclaimed Land", Proceedings of the Korean Geotechnical Society, Gwangju, Korea, pp.1717-1726
  12. Kim, S. I., Park, I. J., and Choi, J. S. (2000), "A Study on the Assesment of Liquefaction potential in Korea", J. of the Korean Society of Civil Engineers, Vol.20, No. 2C, pp.129-139.
  13. Kulhawy, F. H. and Trautmann, C. H. (1996), "Estimation of insitu test uncertainty", Proceedings of uncertainty 96, Geotechnical Special Publication No.58, pp.269-286.
  14. Kulhawy, F. H. (1992), "On evaluation of static soil properties", In Stability and performance of slopes and embankments II (GSP 31). Edited by R.B. Seed and R.W. Boulanger. American Society of Civil Engineers, New York, pp.95-115.
  15. Lacasse, S. and Nadim, F. (1996), "Uncertainties in characteristic soil properties", Proceedings of Uncertainty 96, Geotechnical Special Publication No.58, pp.49-75.
  16. Lee, M. S. (2002), "Effect of clay content on liquefaction resistance of soils", MS. thesis, Inha University, Incheon, Korea.
  17. Lumb, P. (1971), "Precision and accuracy of soil tests", Proceedings of the 1st International Conference on Applications of Statistics and Probability in Soil and Structural Engineering, Hong Kong, pp.329-345.
  18. Olsen, R. S. (1984), "Liquefaction analysis using the cone penetrometer test", Proceedings of 8th World Conference on Earthquake Engineering EERI, San Francisco.
  19. Orchant, C. J., Kulhawy, F. H., and Trautmann, C. H. (1988), "Reliability based foundation design for transmission line structures: critical evaluation of in situ test methods", Electric Power Research Institute, Report EL-5507(2), Palo Alto, CA.
  20. Phoon, K. K., Kulhawy, F. H., and Grigoriu, M. D. (1995), "Reliability-based design of foundations for transmission line structures", Electric Power Research Institute, Report TR-105000, Palo Alto, CA.
  21. Robertson, P. K. and Wride, C. E. (1998), "Evaluating Cyclic Liquefaction Potential Using the Cone Penetration Test", Can. Geotech. J., Vol.35, pp.442-459 https://doi.org/10.1139/t98-017
  22. Robertson, P. K. (2010), "Soil behaviour type from the CPT: an update", Proceedings of 2nd International Symposium on Cone Penetration Testing, CPT 10, Huntington Beach, CA.
  23. Robinson, K., Cubrinovski, M., and Bradley, B. A. (2013), "Comparison of actual and predicted measurements of liquefaction-induced lateral displacements from the 2010 Darfield and 2011 Christchurch Earthquakes", Proceedings of 2013 Conference of the New Zealand Society for Earthquake Engineering, Wellington, New Zealand, pp.26-28.
  24. Ronold, K. O. (1992), "Model Uncertainty Representation in Geotechnical Reliability Analysis", J. of Geotechnical Engineering, Vol.118, No.3, pp.363-376. https://doi.org/10.1061/(ASCE)0733-9410(1992)118:3(363)
  25. Sancio, R. B. (2003), "Ground failure and building performance in Adapazari, Turkey", Ph.D. thesis, University of California, Berkeley, CA.
  26. Seed, H. B. and Idriss, I. M. (1971), "Simplified Procedure for Evaluating Soil Liquefaction Potential", J. of the Soil Mechanics and Foundation Division, Vol.97, No.9, pp.1249-1273. https://doi.org/10.1061/JSFEAQ.0001662
  27. Stuedlein, A. W., Gianella, T. N., and Canivan, G. (2016), "Densification of Granular Soils using Conventional and Drained Timber Displacement Piles", J. Geotech. Geoenviron. Eng., Vol.142, No. 12, 04016075.
  28. Suzuki, Y., Sanematsu, T., and Tokimatsu, K. (1998), "Correlation between SPT and seismic CPT", In: Robertson PK, Mayne PW (eds.), Proceedings of conference on Geotechnical Site Characterization, Balkema, Rotterdam, pp.1375-380.
  29. Whitman, R. V. (2000), "Organizing and Evaluating Uncertainty in Geotechnical Engineering", J. Geotech. Geoenviron. Eng., Vol. 126, No.7, pp.583-593. https://doi.org/10.1061/(ASCE)1090-0241(2000)126:7(583)
  30. Yi, F. (2014), "Estimating soil fines contents from CPT data", Proceedings of 3rd International Symposium on Cone Penetration Testing, Las Vegas, Nevada.
  31. Zhou, S. (1980), "Evaluation of the liquefaction of sand by static cone penetration test", Proceedings of 7th World Conference on Earthquake Engineering, Istanbul, Turkey, Vol.3, pp.156-162.