Journal of the Korean Geosynthetics Society (한국지반신소재학회논문집)

Korean Geosynthetics Society (한국지반신소재학회)
권호 표지
DOI QR코드

DOI QR Code

Calculation of Damping Ratio Using Non-Linear Soil Models and Comparison between Measured and Predicted Data

흙의 비선형 모델을 이용한 감쇠비 산정 및 비교

  • Lee, Hyoung-Kyu (Department of Civil Engineering, Seoil University) ;
  • Bae, Yoon-Shin (Environmental and Safety Research Division, Seoul Development Institute)
  • 이형규 (서일대학 토목공학과) ;
  • 배윤신 (서울시정개발연구원 환경안전연구실)
  • Received : 2011.03.07
  • Accepted : 2011.06.16
  • Published : 2011.06.30
Download PDF
⟨ Previous Next ⟩

Abstract

Several theoretical soil nonlinear models to predict damping ratio, which is one of the typical dynamic properties of soils, it is impractical to predict damping ratio. The resonant column and torsional shear test(RC-TS) is used to represent the dynamic behavior of soils from intermediate to medium shear strains. A limitation of RC-TS is measure precise shear strain in large strains and the modified equivalent radius($R_{eq}$) was obtained using both modified hyperbolic model and Ramberg-Osgood model. Bonneville clays were tested using RC-TS test to obtain rotation and torque. The measured rotation and torque were then compared with calculated rotation and torque using curve-fitting method. Then, the nonlinear soil model parameters were obtained and the equivalent radius was calculated using the model parameters.

지반의 대표적 동적 물성치중 하나인 감쇠비를 구하기 위한 여러 이론적 비선형모델이 개발되어 왔으나 실제 측정된 감쇠비를 정확히 예측하기는 불가능하다. 공진주/비틂전단 시험기는 미소변형율에서 중간변형율까지 흙의 동적 거동을 표현하는데 자주 이용되어 왔다. 공진주/비틂전단 시험기의 단점중의 하나는 측정된 감쇠비에 상응하는 변형율 산정법이 복잡하다는 것이다. 이를 해결하기 위하여 수정쌍곡선 모델과 Ramberg-Osgood모델을 사용하여 수정등가반경법을 도입하여 보다 정확한 변형율을 계산하였다. 유타지역에서 채취된 시료를 이용하여 공진주/비틂전단 시험기로 측정된 비틂력-비틂각을 이론적 비틂력-비틂각과 비교하고, 맞춤곡선법을 사용하여 각 비선형모델의 매개변수를 구하였으며 적합모델별 매개변수에서의 등가반경을 산정하였다.

Keywords

References

  1. Bae, Y.S. (2008), Modeling soil behavior in large strain resonant column and torsional shear tests, PhD Thesis, Utah State University.
  2. Chen, A.T.F., and Stokoe, K.H. (1979) Interpretation of strain dependent modulus and damping from torsional soil tests, Rep. No. USGS-GD-79-002, NTIS No. PB-298479, U.S. Geological Survey, 46.
  3. Hardin, B.O. and Drnevich, V.P. (1972), "Shear modulus and damping in soils: measurement and parameter effects." J. Soil Mech. and Found. Div., ASCE, 98 (6), 603-624.
  4. Ishihara, K. (1996). Soil behavior in earthquake geotechnics. Oxford University Press, Oxford.
  5. Kim, D.S. (1991), Deformational characteristics of soils at small strains from cyclic tests, PhD Thesis, Univ. of Texas Austin, Texas.
  6. Kokusho, T. (1987), "In situ Dynamic Soil Properties and Their Evaluations," Proc. of the Eighth Asian Regional Conference on Soil Mechanics and Foundation Engineering, Kyoto, Vol.2, pp.215-240.
  7. Masing, G. (1926), "Eigenspannungen und Verfestgung Beim Messing", Proc. of Second Int. Conc. of Applied Mech., pp.332-335.
  8. Sasanakul, Inthuorn (2005), Development of an electromagnetic and mechanical model for a resonant column and torsional shear testing device for soils, Ph.D Thesis, Utah State University.
  9. Sasanakul, I. and Bay, J. (2008a), "Stress integration approach in resonant column and torsional shear testing for soils", Journal of geotechnical and geoenvironmental engineering, Vol.134, No.12, pp.1757-1762. https://doi.org/10.1061/(ASCE)1090-0241(2008)134:12(1757)
  10. Sasanakul, I., Bay, J., and Bae, Y. (2008b), "Stress integration approach for soil damping measurements in torsional testing", Proc. of the 4th decennial geotechnical earthquake engineering and soil dynamics conference, Sacramento, CA, May 18-22.
  11. Utah State University (2009), Dynamic properties of Bonneville clay, presented at Eng. Geology and Geotechcnial Eng. Symposium.