Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
권호 표지
DOI QR코드

DOI QR Code

Soil Water Characteristic Curve Using Volumetric Pressure Plate Extractor Incorporated with TDR System

TDR 측정시스템이 도입된 압력판 추출 시험기를 이용한 흙-함수특성곡선 연구

  • Jung, Young-Seok (School of Civil, Environmental and Architectural Engrg., Korea Univ.) ;
  • Sa, Hee-Dong (School of Civil, Environmental and Architectural Engrg., Korea Univ.) ;
  • Kang, Seonghun (School of Civil, Environmental and Architectural Engrg., Korea Univ.) ;
  • Oh, Se-Boong (Department of Civil Engrg., Yeungnam Univ.) ;
  • Lee, Jong-Sub (School of Civil, Environmental and Architectural Engrg., Korea Univ.)
  • 정영석 (고려대학교 건축사회환경공학부) ;
  • 사희동 (고려대학교 건축사회환경공학부) ;
  • 강성훈 (고려대학교 건축사회환경공학부) ;
  • 오세붕 (영남대학교 건설시스템공학과) ;
  • 이종섭 (고려대학교 건축사회환경공학부)
  • Received : 2015.02.11
  • Accepted : 2015.07.10
  • Published : 2015.08.31
Download PDF
⟨ Previous Next ⟩

Abstract

The purpose of this study is to measure the volumetric water content of unsaturated soils during drying and wetting process by using volumetric pressure plate extractor (VPPE) incorporated with time domain reflectometry (TDR). The VPPE consists of a pressure cell, a pressure regulator, a burette system and a TDR probe. Two samples with different initial void ratios were prepared in the pressure cell, and the air pressure at the range of 0.1 kPa - 50 kPa was applied to adjust the matric suction by the pressure regulator. The burette system was used to measure the volumetric water content change of the sample according to the matric suction. In addition, the TDR probe, installed in the cell, was used to evaluate the dielectric constant from the reflected signal of the electromagnetic wave at the probe. The volumetric water content of specimen was estimated by the empirical equation between the volumetric water content and dielectric constant, which was calibrated with the Jumunjin sand. The test results show that the volumetric water content calculated by TDR probe is strongly correlated to the measured value by burette system. The hysteresis occurs during drying and wetting process. Furthermore, the degree of hysteresis reduces in the repeated process. This study suggests that TDR may be effectively used to evaluate the water content soil for the determination of water characteristic curve of unsaturated soils.

흙-함수특성곡선에 대한 선행 연구결과들의 경우, 정량적으로 간극수 유출입량을 측정하여 모관흡수력에 따른 체적함수비를 산정하였다. 본 연구에서는, 압력판 추출시험기(VPPE)에 Time Domain Reflectimoetry(TDR) 측정 시스템을 도입하여 불포화토의 건조과정 및 습윤과정 진행에 따른 유전상수를 측정하여 체적함수비를 산정하고자 하였다. 압력판 추출 시험기는 압력셀, 압력조절장치, 뷰렛 시스템, TDR 프로브로 구성된다. 압력셀에 초기 간극비가 다른 두 시료를 조성한 후, 압력조절장치를 이용하여 압력셀 내부에 0.1kPa - 50kPa 범위의 공기압을 가하여 모관흡수력을 조절하였다. 그리고 뷰렛시스템을 이용하여 모관흡수력 변화에 따른 시료의 체적함수비 변화를 측정하였다. 또한, 압력셀 내부에 설치된 TDR 프로브를 이용하여 프로브 양단에서 발생되는 전자기파의 반사 신호로부터 유전상수를 산정하였다. 주문진 표준사의 체적함수비 변화에 따른 유전상수 측정에 대한 보정으로 도출한 체적함수비와 유전상수관계를 이용하여 시료의 체적함수비를 산정하였다. 실험 결과, 시료의 초기 간극비와 상관없이 TDR 프로브에 의해 산정된 체적함수비는 뷰렛 시스템을 통해 정량적으로 산정된 체적함수비와 매우 유사한 것으로 나타났다. 또한, 건조과정 및 습윤과정 진행에 따라 동일한 모관흡수력에 대한 함수비의 차이가 존재하는 이력현상(Hysteresis)이 발생하였고, 건조과정 및 습윤과정의 반복에 따라 이력현상은 줄어들었다. 본 연구에서 적용된 전자기파의 시간영역반사법(TDR)을 통해 불포화토의 흙-함수특성곡선을 효과적으로 파악할 수 있을 것으로 판단된다.

Keywords

References

  1. Amato, M. and Ritchie, J. T. (1995), "Small Spatial Scale Soil Water Content Measurement with Time-domain Reflectometry", Soil Science Society of America Journal, Vol.59, No.2, pp.325-329. https://doi.org/10.2136/sssaj1995.03615995005900020008x
  2. Assouline, S. (2006), "Modeling the Relationship between Soil Bulk Density and the Hydraulic Conductivity Function", Vadose Zone Journal, Vol.5, No.2, pp.697-705. https://doi.org/10.2136/vzj2005.0084
  3. ASTM D854-10 (2005), "Standard Test Methods for Specific Gravity of Soil Solids by Water Pyconometer", Annual Book of ASTM Standard, Vol.04.08.
  4. ASTM D4253-00 (2006), "Standard Test Methods for Maximum Index Density and Unit Weight for Soils Using a Vibration Table", Annual Book of ASTM Standard, Vol.04.08
  5. ASTM D4254-00 (2006), "Standard Test Methods for Minimum Index Density and Unit Weight for Soils Calculation of Relative Density", Annula Book of ASTM Standard, Vol.04.08
  6. Barbour, S. L. (1998), "Nineteenth Canadian Geotechnical Colloquium: The Soil-water Characteristic Curve: A Historical Perspective", Candadian Geotechnical Journal, Vol.35, No.5, pp.873-894. https://doi.org/10.1139/t98-040
  7. Bear, J. (1979), "Hydraulic of Groundwater", McGraw-Hill, New York, pp.567.
  8. Benson, C. and Bosscher, P. (1999), "Time-domain Reflectometry in Geotechnics: A Review", Nondestructive and Automated Testing for Soil and Rock Properties, STP 1350, ASTM, W. Marr and C. Farihurst, Eds., pp.113-136.
  9. Byun, Y. H., Cho, S. H., Yoon, H. K., Choo, Y. W., Kim, D. S., and Lee, J. S. (2012), "Void Ratio Evaluation of Unsaturated Soils by Compressional and Shear Waves", Journal of the Korean Geotechnical Society, Vol.28, No.12, pp.41-51. https://doi.org/10.7843/kgs.2012.28.12.41
  10. Cassel, D. K., Kachanoski, R. G., and Topp, G. C. (1994), "Practical Considerations for Using a TDR Cable Tester", Soil technology, Vol.7, No.2, pp.113-126. https://doi.org/10.1016/0933-3630(94)90013-2
  11. Davis, J. L. and Chudobiak, W. J. (1975), "Relative Permittivity Measurements of a Sand and Clay Soil in Situ", Geological Survey of Canada, Paper, pp.361-365.
  12. Fredlund, D. G. and Rahardjo, H. (1993), "Flow Lows", Soil Mechanics for Unsaturated Soils, John Wiley & Sons, New York, pp.107-123.
  13. Fredlund, D. G. and Xing, A. (1994), "Equations for the Soil-water Characteristic Curve", Canadian Geotechnical Journal, Vol.31, No.4, pp.521-532. https://doi.org/10.1139/t94-061
  14. Fredlund, D. G. (2002), "Use of Soil-water Characteristic Curve in the Implementation of Unsaturated Soil Mechanics", Proceedings of the 3rd International Conference on Unsaturated Soils, Recife, pp.20-23.
  15. Fredlund, D. G. (2006), "Unsaturated Soil Mechanics in Engineering Practice", Journal of Geotechnical and Geoenvironmental Engineering, Vol.132, No.3, pp.286-321. https://doi.org/10.1061/(ASCE)1090-0241(2006)132:3(286)
  16. Heimovaara, T. J. (1993), "Design of Triple-wire Time Domain Reflectometry Probes in Practice and Theory", Soil Science Society of America Journal, Vol.57, No.6, pp.1410-1417. https://doi.org/10.2136/sssaj1993.03615995005700060003x
  17. Herkelrath, W. N., Hamburg, S. P., and Murphy, F. (1991), "Automatic, Real-time Monitoring of Soil Moisture in a Remote Field Area with Time Domain Reflectometry", Water Resources Research, Vol.27, No.5, pp.857-864. https://doi.org/10.1029/91WR00311
  18. Hillel, D. and Mottas, J. (1966), "Effect of Plate Impedance, Wetting Method and Aging on Soil Moisture Retention", Soil Science, Vol.102, No.2, pp.135-139. https://doi.org/10.1097/00010694-196608000-00009
  19. Hillel, D. (1971), "Soil and Water", Academic Press, New York.
  20. Hillel, D. (1998), "Environmental Soil Physic", Academic Press, San Diego, USA.
  21. Hoekstra, P. and Delaney, A. (1974), "Dielectric Properties of Soils at UHF and Microwave Frequencies", Journal of Geophysical Research, Vol.79, No.11, pp.1699-1708. https://doi.org/10.1029/JB079i011p01699
  22. Hwang, C. S. and Kim, T. H. (2004), "Determination of the Unsaturated Hydraulic Conductivity of Function", Journal of the Korean Geotechnical Society, Vol.20, No.3, pp.47-51.
  23. Hwang, W. K., Kang, K. M., Kim, T. H., and Song, Y. S. (2012), "Effect of Soil Structure on Soil-water Characteristic in Unsaturated Soil", Journal of the Korean Geotechnical Society, Vol.28, No.2, pp.33-42. https://doi.org/10.7843/kgs.2012.28.2.33
  24. Jones, S. B., Wraith, J. M., and Or, D. (2002), "Time Domain Reflectometry Measurement Principles and Applications", Hydrological Processes, Vol.16, No.1, pp.141-153. https://doi.org/10.1002/hyp.513
  25. Kumar, S. and Malik, R. S. (1990), "Verification of Quick Capillary Rise Approach for Determining Pore Geometrical Characteristics in Soils of Varying Texture", Soil Science, Vol.150, No.6, pp.883-888. https://doi.org/10.1097/00010694-199012000-00008
  26. Lin, Y., Schanz, T., and Fredlund D. G. (2009), "Modified Pressure Plate Apparatus and Column Testing Device for Measuring SWCC of Sand", Geotechnical Testing Journal, ASTM, Vol.32, No.5, pp.1-15.
  27. Lu, N. and Likos, W. J. (2004), "Unsaturated Soil Mechanics", John Wiley and Sons Inc., Hoboken, New Jersey.
  28. Nishimura, T., Koseki, J., Fredlund, D. G., and Rahardjo, H. (2012), "Microporous Membrane Technology for Measurement of Soil-water Characteristic Curve", Geotechnical Testing Journal, ASTM, Vol.35, No.2, pp.201-208.
  29. O'Connor, K. M. and C. H. Dowding (1999), "Geomeasurements by Pulsing TDR Cables and Probes", CRC Press.
  30. Padilla, J. M., Perera, Y. Y., Houstion, W. N., Perez, N., and Fredlund, D. G. (2006), "Quantification of Air Diffusion through High Air-entry Ceramic Disk", Proceedings of the Fourth International Conference on Unsaturated Soils, UNSAT 2006, Carefree, Arizona, April 2-6, Vol.2, pp.1852-1863.
  31. Ranjan, R. S. and Domytrak, C. J. (1997), "Effective Volume Measured by TDR Miniprobes", Transactions of the ASAE, Vol.40, No.4, pp.1059-1066. https://doi.org/10.13031/2013.21358
  32. Robinson, D. A., Jones, S. B., Wraith, J. M., Or, D., and Friedman, S. P. (2003), "A Review of Advances in Dielectric and Electrical Conductivity Measurement in Soils Using Time Domain Reflectometry", Vadose Zone Journal, Vol.2, No.4, pp.444-475. https://doi.org/10.2136/vzj2003.4440
  33. Soilmoisture Equipment Corporation (2005), "Volumetric Pressure Plate Extractor and Hysteresis Attachments", Operating Instructions: Model 1250, Santabarbara, CA, USA, pp.1-12.
  34. Song, Y. S., Lee, N. W., Hwang, W. K., and Kim, T. H. (2010), "Construction and Application of an Automated Apparatus for Calculating the Soil-water Characteristic Curve", Journal of Engineering Geology, Vol.20, No.3, pp.281-295.
  35. Song, Y. S. (2013), "Estimation on Unsaturated Hydraulic Conductivity Function of Jumoonjin Sand for Various Relative Densities", Journal of the Korean Society of Civil Engineers, Vol.33, No.6, pp.2369-2379. https://doi.org/10.12652/Ksce.2013.33.6.2369
  36. Tinjum, J. M., Benson, C. H., and Blotz, L. R. (1997), "Soil-water Characteristic Curves for Compacted Clays", J. Geotech Geoenviron. Eng., Vol.123, No.11, pp.1060-1069. https://doi.org/10.1061/(ASCE)1090-0241(1997)123:11(1060)
  37. Topp, G. C., Davis, J. C., and Annan, A. P. (1980), "Electromanetic Determination of Soil Water Content: Measurements in Coaxial Transmission Lines", Water Resources Research, Vol.16, No.3, pp.574-582. https://doi.org/10.1029/WR016i003p00574
  38. Vanapalli, S. K., Fredlund, D. G., and Pufahl, D. E. (1999), "The Influence of Soil Structure and Stress History on the Soil-water Characteristics of a Compacted Till", Geotechnique, Vol.49, No.2, pp.143-159. https://doi.org/10.1680/geot.1999.49.2.143
  39. White, I. and Zegelin, S. J. (1995), "Electric and Dielectric Methods for Monitoring Soil-water Content", Handbook of vadose zone characterization and monitoring, pp.343-385.
  40. Yang, H., Rahardjo, H., Leong, E. C., and Fredlund, D. G. (2004), "Factors Affecting Drying and Wetting Soil-water Characteristic Curves of Sandy Soils", Canadian Geotechnical Journal, Vol.41, No.5, pp.908-920. https://doi.org/10.1139/t04-042