Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Study of Confidence Ranges for Field Phase Difference Measurement Data Collected using Geophones

지오폰을 활용한 현장 위상각차 계측 데이터 신뢰 구간에 관한 기초 연구

  • Kim, Gunwoong (Korea Institute of Civil Engineering and Building Technology, KICT)
  • 김건웅 (한국건설기술연구원 지반연구본부)
  • Received : 2024.04.30
  • Accepted : 2024.05.27
  • Published : 2024.06.30
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Abstract

Regular monitoring plays a crucial role in ensuring the safety of geotechnical structures. Currently, nondestructive methods are employed to monitor such structures to minimize the impact, e.g., sensor-based accelerometers, displacement meters, image-based lasers, and drone imaging. These technologies can observe surface changes; however, they frequently suffer difficulties in terms of identifying changes in internal properties. To monitor changes in internal properties, in situ geotechnical investigations can be employed. A nondestructive test that can be used for this purpose is the spectral analysis of surface wave (SASW) test using geophones. The SASW test is a nondestructive method; however, due to the time required for data interpretation and the difficulty in analyzing the data, it is challenging to use the SASW test for monitoring applications that require frequent observations. However, it is possible to apply the first-step analysis, which yields the dispersion curve, for monitoring rather than the complete SASW analysis, which yields the shear wave velocity. Thus, this paper presents a fundamental study on the phase difference that derives the dispersion curve to utilize the SASW test for monitoring. The reliability of each phase difference interval is examined to determine the boundary to the subjected monitor. The study used phase difference data obtained using a geophone from a single-layered, homogeneous ground site to evaluate reliable boundaries. The findings of this study are expected to improve the utility of monitoring by identifying the ideal boundary for phase difference data.

건설된 지반구조물을 안전하게 유지하기 위해 정기적인 모니터링은 매우 중요하다. 현재 유지관리를 위해 센서를 기반으로 하는 가속도, 변위계, 이미지를 기반으로 하는 레이저 혹은 드론 영상 촬영 등 지반구조물에 영향을 최소화할 수 있는 비파괴방식이 활용되고 있다. 해당 기술들은 표면의 변화를 관찰할 수 있지만, 내부 물성값 변화 파악에는 어려움이 있다. 지반구조물의 내부 물성값 변화를 모니터링하기 위해 현장 지반조사법이 도입될 수 있으며, 이를 위해 활용될 수 있는 비파괴시험에는 지오폰을 활용한 Spectral-Anlysis-of-Surface-Wave(SASW) 시험이 있다. SASW 시험은 비파괴시험이지만, 데이터 해석에 드는 시간과 분석에 어려움으로 인해 잦은 관찰을 요구하는 유지관리 모니터링의 용도로 활용이 어렵다. 하지만, 전단파 속도를 도출하는 복잡한 SASW 최종 해석이 아닌 분산곡선을 도출하는 1단계 해석만으로도 모니터링에 적용할 수 있다. 따라서, 본 논문에서는 SASW 시험을 모니터링에 활용하기 위해 분산곡선 도출에 필요한 위상각차 데이터에 관한 기초 연구를 수행하였다. 위상각차 구간별 신뢰도에 대해 검토하여 데이터 모니터링에 활용이 가능한 범위에 관하여 확인하였다. 이를 위해 단일 층으로 구성된 균질한 지반 현장에서 지오폰을 활용하여 계측한 위상각차 데이터들을 활용하였다. 본 연구를 통해 활용할 수 있는 위상각차 데이터 구간을 파악해 모니터링의 활용성을 높일 것으로 기대된다.

Keywords

References

  1. Born, M., Wolf, E. (1999), Principles of Optics, Cambridge University Press. 
  2. Cho, M. and Kang, T. (2003), "Application of the SASW Method to the Evaluation of Grouting Performance for a Soft Ground of a Tunnel", Journal of the Korean Geotechnical Society, Vol.19, No.6, pp.273-283. (in Korean) 
  3. Foti, S., Hollender, F., Garofalo, F., Albarello, D., Asten, M., Bard, P. Y., and Forbriger, T. (2018), "Guidelines for the Good Practice of Surface Wave Analysis: A Product of the InterPACIFIC Project", B. Earthq. Eng., Vol.16, No.6, pp.2367-2420.  https://doi.org/10.1007/s10518-017-0206-7
  4. Haegeman, W. and Van Impe, W. F. (1999), "Characterization of Disposal Sites from Surface Wave Measurements", Journal of Environmental Engineering and Geophysics, 4, 27. 
  5. Hecht, E. (2002), Optics (4th ed.), Addison Wesley. 
  6. Joh, S. H. (1996), Advances in the data interpretation technique for Spectral-Analysis-of-Surface-Waves (SASW) measurements (Doctoral dissertation, The University of Texas at Austin). 
  7. Joh, S. H., Jang, D. W., Kang, T. H., and Lee, I. W. (2005), "Evaluation of Stiffness Profile for a Subgrade Cross-Section by the CAP (Common-Array-Profiling)-SASW Technique", Journal of the Korean Geotechnical Society, Vol.21, No.4, pp.71-81. (in Korean) 
  8. Kausel, E. and Peek, R. (1982), "Dynamic Loads in the Interior of a Layered Stratum: An Explicit Solution", Bulletin of the Seismological Society of America, Vol.72, No.5, pp.1459-1481.  https://doi.org/10.1785/BSSA0720051459
  9. Kausel, E. and Roesset, J. M. (1981), "Stiffness Matrices for Layered Soils", Bulletin of the Seismological Society of America, Vol.71, pp.1743-1761.  https://doi.org/10.1785/BSSA0710061743
  10. Kim, B., Cho, A., Cho, S. O., Nam, M. J., Pyun, S., and Hayashi, K. (2019), "Surface Wave Method: Focused on Active Method", Geophysics and Geophysical Exploration, Vol.22, No.4, pp.210-224.  https://doi.org/10.7582/GGE.2019.22.4.210
  11. Kim, D. S., Shin, M. K., and Park, H. C. (2001), "Evaluation of Density in Layer Compaction Using SASW Method", Soil Dynamics and Earthquake Engineering, Vol.21, pp.39-46.  https://doi.org/10.1016/S0267-7261(00)00076-2
  12. Kim, G. (2023), "Evaluation of Ground Compaction Using SASW Testing", Journal of the Korean Geosynthetics Society, Vol.22, No.4, pp.9-15. (in Korean)  https://doi.org/10.12814/JKGSS.2023.22.4.009
  13. Kim, G., Hwang, S., and Stokoe, II K. H. (2022), "Evaluation of the Lateral Variability in the Vs Profiles at Geotechnical Sites using the Spectral-Analysis-of-Surface-Waves (SASW) Method", Paper presented at the 12th National Conference on Earthquake Engineering, Paper Number 10181. 
  14. Lee, H.-C., Kwon, K., Moon, C., and Jo, Y. (2018), "Survey Equipment Development of Stability Evaluation for Rock Slope using Drone", Journal of the Korea Institute for Structural Maintenance and Inspection, Vol.22, No.4, pp.91-99. (in Korean)  https://doi.org/10.11112/JKSMI.2018.22.4.091
  15. Lee, Y., Kim, H.-S., Ju, Y.-T., Kim, D., Park, H.-J., and Park, D. (2021), "Dynamic Factor of Safety Calculation of Slope by Nonlinear Response History Analysis", Journal of the Korean Geotechnical Society, Vol.37, No.9, pp.5-12. (in Korean)  https://doi.org/10.7843/KGS.2021.37.9.5
  16. Maraveas, C. and Bartzanas, T. (2021), "Sensors for Structural Health Monitoring of Agricultural Structures", Sensors, Vol.21, No.1, p.314. 
  17. Mayne, P.W. (2001), "Invited Keynote: 'Stress-Strain-Strength-Flow Parameters from Enhanced In-Situ Tests'", in Proceedings, International Conference on In-Situ Measurement of Soil Properties & Case Histories (In-Situ 2001), Bali, Indonesia, pp.27-47. 
  18. Mayne, P.W. (2005), "Invited Keynote: Integrated Ground behavior: In-situ and Lab Tests", in Proceedings of IS Lyon'03, Deformation Characteristics of Geomaterials, Taylor & Francis Group, London, 2, pp.155-177. 
  19. Nazarian, S. and Stokoe, K. H. (1984), "In Situ Shear Wave Velocities from Spectral Analysis of Surface Waves", In Proceedings of the 8th World Conference on Earthquake Engineering, 3, 31-38. Prentice-Hall. 
  20. Park, D., Yu, J.-I., and You, H. (2023), "A Research on Applicability of Drone Photogrammetry for Dam Safety Inspection", Journal of the Korea Institute for Structural Maintenance and Inspection, Vol.27, No.5, pp.30-39. (in Korean)  https://doi.org/10.11112/JKSMI.2023.27.5.30
  21. Rix, G. J., Lai, C. G., Foti, S., and Zywicki, D. (1998), "Surface Wave Tests in Landfills and Embankments", ASCE Geotechnical Special Publication, Vol.75, No.2, pp.1008-1019. 
  22. Stokoe, II, K.H., Kim, G., and Hwang, S. (2021), "Shear Wave Velocity Profiling Using the SASW Method at Four Nuclear Power Plant Sites (NPP1, NPP2, NPP3, and NPP4) in Taiwan", Geotechnical Engineering Report GR21-13, University of Texas at Austin, August 2021. 
  23. Stokoe, K. H. and Nazarian, S. (1985), Measurement and use of shear wave velocity for evaluating dynamic soil properties, In R. D. Woods (Ed.), Use of Rayleigh waves in liquefaction Studies, 187-196. ASCE. 
  24. Stokoe, K. H., Cox, B., Clayton, P., and Menq, F. (2017), NHERI@ UTEXAS Experimental Facility: Large-scale Mobile Shakers for Natural-hazards Field Studies, Paper presented at the 16th World Conference on Earthquake Engineering, Santiago, Chile, Paper No. 2387. 
  25. Stokoe, K. H., Hwang, S., and Joh, S. H. (2017), "Spectral-Analysis-of-Surface-Waves (SASW) Testing to Evaluate Vs Profiles at Geotechnical and Geological Sites", Paper presented at the 16th World Conference on Earthquake Engineering, Santiago, Chile, Paper No. 4948.
  26. Yoon, G. H., Kim, S. K., Kang, Y. H., and Kang, M. J. (2021), "A Study on the Establishment of a Smart Dam Safety Management System", Paper presented at the Korean Society of Civil Engineers Annual Conference, Venue: KSCE 2021 CONVENTION. 
  27. Yuan, J., Zhu, J., and Kim, C. (2014), "Comparison of SASW and MASW Methods Using MSOR Approach - A Case Study", International Journal of Geotechnical Engineering, Vol.8, No.2, pp.233-238. https://doi.org/10.1179/1938636213Z.00000000077