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온도와 포화도의 변화에 의한 표면장력이 전단파 속도에 미치는 영향

The Effect of Surface Tension on Shear Wave Velocities according to Changes of Temperature and Degree of Saturation

  • 박정희 (고려대학교 건축사회환경공학부) ;
  • 강민구 (고려대학교 건축사회환경공학부) ;
  • 서선영 (고려대학교 건축사회환경공학부) ;
  • 이종섭 (고려대학교 건축사회환경공학부)
  • 투고 : 2012.08.09
  • 심사 : 2012.09.28
  • 발행 : 2012.11.15

초록

표면장력에 의한 겉보기 점착력은 적절한 함수비를 가지고 있는 흙의 경우 생성되며 지반의 강도를 증가시킨다. 본 연구의 목적은 온도에 따라 변화하는 표면장력이 전단파 속도에 미치는 영향을 파악하는 것이다. 표면장력의 발생 유무를 조절하기 위하여 모래-실트 혼합토를 이용하여 포화도가 다른 아홉 가지의 시료 (0%, 2.5%, 5%, 10%, 20%, 40%, 60%, 80%, 100%)를 조성하였다. 전단파 속도를 측정하기 위해 나일론 재질의 셀을 제작하였으며 전단파 트랜스듀서인 벤더 엘리먼트를 크로스 홀 형상으로 부착하였다. 시료의 온도가 $15^{\circ}C$에서 $1^{\circ}C$까지 변화하는 동안 포화도가 다른 각 시료의 전단파 신호를 연속적으로 측정하였다. 실험결과, 포화도 0%인 시료와 포화도 100%인 시료는 온도변화에 의한 전단파 속도 변화가 미비하였으나, 표면장력이 발생하기에 적절한 포화도를 가진 시료는 온도가 감소함에 따라 전단파 속도는 증가하였다. 또한 완전 포화된 시료를 $70^{\circ}C$에서 건조시키면서 포화도에 따른 전단파 속도를 측정한 시료의 경우, $15^{\circ}C$에서 측정된 시료의 전단파 속도보다 더 낮은 전단파 속도가 측정되었다. 본 연구는 특정한 포화도에서 온도변화에 따라 전단파 속도가 변화하는 원인을 실험을 통해 분석하였으며, 미소변형구간에서의 전단탄성계수 측정과 같은 실내 및 현장실험 시, 온도를 동시에 평가해야 함을 보여준다.

The surface tension, which is generated in the unsaturated soils, increases the stiffness of the soils. The objective of this study is to estimate the effect of the surface tension, which varies according to the temperature, on the shear wave velocity. Nine specimens, which have the different degree of saturation (0%, 2.5%, 5%, 10%, 20%, 40%, 60%, 80%, 100%), are prepared by using sand-silt mixtures. Experiments are carried out in a nylon cell designed for the measurement of shear waves. A pair of bender elements, which are used for the generation and detection of shear waves, is installed as a cross-hole type. The shear waves are continuously monitored and measured as the temperature of specimens decreases from $15^{\circ}C$ to $1^{\circ}C$. The results show that shear wave velocities of the fully saturated and fully dried specimens change a little bit as the temperatures of specimens decrease. However, the shear wave velocities of the specimens with the degree of saturations of 2.5%, 5%, 10%, 20%, 40%, 60% and 80% continuously increase as temperature decreases from $15^{\circ}C$ to $1^{\circ}C$. Furthermore, a fully saturated specimen is dried at the temperature of $70^{\circ}C$ in order to observe the shear waves according to degree of saturation. The shear wave velocities measured at the temperature of $70^{\circ}C$ are generally lower than those measured at temperature of $15^{\circ}C$. This study demonstrates that the dependence of shear wave velocities on the temperature according to the degree of saturation should be taken into account in both laboratory and field tests.

키워드

참고문헌

  1. 박정희, 홍승서, 김영석, 이종섭(2012) 흙의 동결에 의한 모래-실트 혼합토의 탄성파 특성, 한국지반환경공학회 논문집, 한국지반환경공학회, 제13권 제4호, pp. 27-36.
  2. 이세현, 서원석, 윤준웅, 김동수(2006) 모관흡수력 조절을 이용한 다짐 후 함수비 변화에 따른 노상토의 탄성계수 평가를 위한 시스템 개발, 한국도로학회 학술발표회, 한국도로학회, pp. 85-94.
  3. 이종섭, 이창호 (2006), 벤더엘리먼트 시험의 원리와 고려사항, 한국지반공학회 논문집, 한국지반공학회, 제22권 제5호, pp. 47-57.
  4. 조계춘, 이인모(2002) 탄성파를 이용한 흙의 특성연구, 한국지반공학회 논문집, 한국지반공학회, 제18권 제6호, pp. 83-101.
  5. ASTM D854-05 (2006) Standard Test Methods for Specific Gravity of Soil Solids by Water Pycnometer, Annual Book of ASTM Standard.
  6. ASTM D4253-00 (2006) Standard Test Methods for Maximum Index Density and Unit Weight of Soils Using a Vibratory Table, Annual Book of ASTM Standard.
  7. ASTM D4254-00 (2006) Standard Test Methods for Minimum Index Density and Unit Weight of Soils Calculation of Relative Density, Annual Book of ASTM Standard.
  8. Bachmann, J. and Ploeg, R. R. (2002) A review on recent developments I soil water retention theory: interfacial tension and temperature effects, Journal of plant nutrition and soil science, Vol. 165, No. 4, pp. 468-478. https://doi.org/10.1002/1522-2624(200208)165:4<468::AID-JPLN468>3.0.CO;2-G
  9. Bishop, A. W. and Blight, G. E. (1963), Some aspects of effective stress in saturated and unsaturated soils, Geotechnique, Vol. 13, No. 3, pp. 177-197. https://doi.org/10.1680/geot.1963.13.3.177
  10. Chahal, R. S. (1965) Effect To Temperature and Trapped Air on Matric Suction, Soil sciene, Vol. 100, No. 4, pp. 262-266. https://doi.org/10.1097/00010694-196510000-00006
  11. Cho, G. C. and Santamarina J. C. (2001), Unsaturated particulate materials-particle-level studies, Journal of Geotech Geoenviron Eng, ASCE, Vol. 127, No. 1 pp. 84-96. https://doi.org/10.1061/(ASCE)1090-0241(2001)127:1(84)
  12. Christ, M. and Park, J. B. (2011), Determination of elastic constants of frozen rubber-sand mixes by ultrasonic testing, Journal of cold regions engineering, Vol. 25, No. 4, pp. 196-207. https://doi.org/10.1061/(ASCE)CR.1943-5495.0000028
  13. Dallavalle, J. M. (1943) Micrometric, Pitman, London.
  14. Gittens, G. J. (1968) Variation of Surface Tension of Water with Temperature, Journal of Colloid and Interface Science, Vol. 30, No. 3, pp. 406-412.
  15. Grant, S. A. and Bachmamm, J. B. (2002), Effect of temperature on capillary pressure, Geophysical monograph, Vol. 129, pp. 199-212. https://doi.org/10.1029/129GM18
  16. Hopmans, J. W. and Dane, J. H. (1986), Temperature Dependence of Soil Water Retention Curves1, Soil Science Society of America journal, Vol. 50, No. 3, pp. 562-567. https://doi.org/10.2136/sssaj1986.03615995005000030004x
  17. IAPWS (1994) International Association for the Properties of Water and Steam Release on Surface tension of Ordinary Water Substance.
  18. Kayser, W. B. (1975) Temperature Dependence of the Surface Tension of Water in Contact with Its Saturated Vapor, Journal of Colloid and Interface Science, Vol. 56, No. 3, pp. 622-627.
  19. Kramer, S. L. (1996) Geotechnical earthquake Engineering, Prentice-Hall, Inc., Upper Saddle River.
  20. Lechman, J. and Lu, N. (2008) Capillary Force and Water Retention between Two Uneven-Sized Particles, Journal of Engineering mechanics, ASCE, Vol. 134, No. 5, pp. 374-384. https://doi.org/10.1061/(ASCE)0733-9399(2008)134:5(374)
  21. Lee, J. S. and Santamarina, J. C. (2005a) Bender Elements: Performance and Signal Interpretation. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 131, No. 9, pp. 1063-1070. https://doi.org/10.1061/(ASCE)1090-0241(2005)131:9(1063)
  22. Lee, J. S. and Santamarina, J. C. (2006) Discussion "Measuring Shear Wave Velocity Using Bender Elements" By Leong, E. C., Yeo, S. H., and Rahardjo, H. (Geotechnical Testing Journal, Vol. 28, No. 5), Geotechnical Testing Journal, ASTM, Vol. 29, No. 5, pp. 439-441.
  23. Likos, W. J. (2009), Pore-Scale Model for Water Retention in Unsaturated Sand, Proceeding of the 6th international conference on Micromechanics of Granular Media, pp. 907-910.
  24. Liu, H. H. and Dane, J. H. (1993), Reconciliation between Measured and Theoretical Temperature Effects on Soil Water Retention Curves, Soil Science Society of America journal, Vol. 57, No. 5, pp. 1202-1207. https://doi.org/10.2136/sssaj1993.03615995005700050007x
  25. Lu, T. X., Biggar, J. W., and Nielsen, D. R. (1994), Water Movement in Glass Beads Porous Media, 2., Experiments of Infiltration and Finger Flow, Water Resour. Res, Vol. 28, pp. 3283-3290.
  26. Molenkemp, F. and Nazemi, A. H. (2003) Interactions between two rough spheres, water bridge and water vapor, Geotechnique, Vol. 53, No. 2, pp. 255-264. https://doi.org/10.1680/geot.2003.53.2.255
  27. Nimmo, J. R. and Miller, E. E. (1986) The temperature dependence of isothermal moisture vs. Potential characteristics of soils, Soil Science Society of America journal, Vol. 50, No. 5, pp. 1105-1113. https://doi.org/10.2136/sssaj1986.03615995005000050004x
  28. Roesler, S. K. (1979) Anisotropic Shear Modulus due to Stress Anisotropy, Journal of Geotechnical Engineering Division, ASCE, Vol. 105 No. 7, pp. 871-880.
  29. Romero, E., Gens, A., and LLotet, A. (2001) Temperature effects on the hydraulic behavior of an unsaturated clay, Geotechnical and Geological Engineering, Vol. 19, pp. 311-322. https://doi.org/10.1023/A:1013133809333
  30. Santamarina, J. C., Klein, K. A., and Fam, M. A. (2001) Soils and Waves - Particulate Materials Behavior, Characterization and Process Monitoring, Wiley, New York.
  31. Sawangsuriya, A., Fall, M., and Fratta, D. (2008), Wave-Based Techniques for Evaluating Elastic Modulus and Poisson's Ratio of Laboratory Compacted Lateritic Soils, Geotechnical and Geological Engineering, Vol. 26, No. 5, pp. 567-578. https://doi.org/10.1007/s10706-008-9190-7
  32. Yu, P. and Richart, F. E. Jr. (1984) Stress Ratio Effects on Shear Modulus of Dry Sands, Journal of Geotechnical Engineering, ASCE, Vol. 110, No. 3, pp. 331-345. https://doi.org/10.1061/(ASCE)0733-9410(1984)110:3(331)
  33. Wilkinson, G. E. and Klute, A. (1962) The Temperature Effect on the Equilibrium Energy Status of Water Held by Porous Media1, Soil Science Society of America Journal, Vol. 26, No. 4, pp. 326-329. https://doi.org/10.2136/sssaj1962.03615995002600040007x

피인용 문헌

  1. Characteristics of Sand-Silt Mixtures during Freezing-Thawing by using Elastic Waves vol.15, pp.5, 2014, https://doi.org/10.14481/jkges.2014.15.5.47
  2. Variation in Characteristics of Elastic Waves in Frozen Soils According to Degree of Saturation vol.33, pp.3, 2013, https://doi.org/10.12652/Ksce.2013.33.3.1063