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Application of Geophysical Techniques for Observing the Void Ratio Changes of Dredged Soils

준설토의 간극비 변화 관찰을 위한 물리탐사기법의 적용

  • Hong, Young-Ho (School of Civil, Environmental and Architectural Engrg., Korea Univ.) ;
  • Lee, Jong-Sub (School of Civil, Environmental and Architectural Engrg., Korea Univ.) ;
  • Lee, Changho (Department of Marine and Civil Engrg., Chonnam National Univ.)
  • 홍영호 (고려대학교 건축사회환경공학부) ;
  • 이종섭 (고려대학교 건축사회환경공학부) ;
  • 이창호 (전남대학교 해양토목공학과)
  • Received : 2014.05.07
  • Accepted : 2014.07.18
  • Published : 2014.09.30

Abstract

It is necessary to understand the behavior of the soils for the dredging constructions. The objective of this study is to estimate void ratio and density changes of the dredged soils by using the geophysical testing methods. A series of laboratory tests is performed to obtain geotechnical index properties of the specimen, retrieved from the west coastal of Korea. The sedimentation and self-weight consolidation tests are carried out with observing changes of the interfacial height and the elastic wave velocities. The same amounts of the soils are poured into the testing column at intervals of 12 hours until the interheight reaches to a certain level. After the completion of the sedimentatation and self-weight consolidation tests, downward permeability test is performed to assess a tidal influence in the nearshore. The mini resistance cone is penetrated into the specimen to measure the electrical resistivity with depth. All tests are completely finished, the weight of specimens are measured to calculate the void ratio with the depth. Experimental results show that the aspects of the self-weight consolidation are invisible during dredging process because of rapid sedimentation characteristics of ML. However, the elastic wave velocities increase with increasing in the effective stresses. During permeability test, measured permeability and the elastic wave velocities maintain almost identical values. Void ratio based on the elastic wave velocities changes linearly with time during the step dumpings. Void ratio estimated by the electrical resistivity represents the repeatedly layered depositions according to the step-by-step dumpings. Void ratio determined by soil sampling is similar to those of elastic waves and electrical resistivity profiles. This experimental study demonstrates that the geophysical testing methods may be an effective method for evaluating the behavior of dredged soils.

해성점토를 활용한 준설매립공사에서는 준설토의 거동분석이 선행되어야 한다. 본 연구에서는 침강압밀하는 준설토의 밀도와 간극비 변화를 관찰하기 위해 물리탐사기법을 적용하였다. 서해안에서 채취한 흙에 대한 기본물성시험을 실시하였고, 침강압밀시험기에 시료를 단계적으로 투기하여 시간에 따른 계면고와 탄성파의 변화를 관찰하였다. 흙의 침강압밀이 완료된 후 하방향의 투수시험을 실시하여 조간대의 영향이 준설토의 물리적 특성에 미치는 영향을 관찰하였다. 또한 초소형 전기저항탐침을 관입하여 깊이에 따른 시료의 전기비저항을 측정하였다. 모든 실험이 완료된 후, 시료를 채취하여 간극비를 계산하였다. 실험결과, ML 시료의 특성상 급격한 침강을 보여 침강압밀특성을 육안으로 관찰하기 어려웠으나, 단계투기가 계속될수록 탄성파의 속도는 증가하는 경향을 보였다. 하방향 투수에 따른 조간대 영향은 매우 적어 관찰할 수 없었다. 한편 탄성파 속도로 추정한 시료의 간극비는 단계투기에 따라 선형적으로 증가하는 경향을 나타내었다. 전기비저항으로부터 계산된 간극비는 깊이에 따라 반복적으로 증가, 감소하는 형태를 나타내었으며 이는 단계투기에 따라 층을 이루고 있는 시료의 영향으로 파악된다. 시료채취, 탄성파 속도, 그리고 전기비저항으로부터 구한 간극비를 비교한 결과, 서로 유사한 관계를 나타내었다. 본 연구는 물리탐사기법이 준설토의 간극비 관찰에 효과적으로 활용될 수 있음을 보여준다.

Keywords

References

  1. Archie, G. E. (1942), "The electrical resistivity log as an aid in determining some reservoir characteristics", Transactions of the American Institute of Mining, Metallugical, and Petroleum Engineers, Vol.146, No.1, pp.54-62.
  2. Been, K. and Sills, G. C. (1981), "Self-weight consolidation of soft soils: an experimental and theoretical study", Geotechnique, Vol.31, No.4, pp.519-535. https://doi.org/10.1680/geot.1981.31.4.519
  3. Bemben, S. M. and Myers, H. J. (1974), "The influence of rate of penetration on static cone resistance in connecticut river valley varved clay", Proceedings of the European Symposium on Penetration Testing, Stockholm, Vol.2, No.2, pp.33-34.
  4. Biot, M. (1956), "Theory of propagation of elastic waves in fluidsaturated porous solid. I. low frequency range", Journal of the Acoustical Society of America, Vol.28, No.2, pp.168-178. https://doi.org/10.1121/1.1908239
  5. Blewett, J., McCarter, W. J., Chrisp, T. M., and Starrs, G. (2001), "Monitoring sedimentation of a clay slurry", Geotechnique, Vol.51, No.8, pp.723-728. https://doi.org/10.1680/geot.2001.51.8.723
  6. Choi, H. S., Kwak, T. H., Lee, C. H., Lee, D. S., and Stark, T. D. (2011), "Analysis method for non-linear finite strain consolidation for soft dredged soil deposit Part II: analysis method and craney island case study", Journal of Korean Geotechnical Society, Vol. 27, No.11, pp.5-15. https://doi.org/10.7843/kgs.2011.27.11.005
  7. Elder, D. McG. (1985), "Stress-strain and strenghth behaviour of very soft soil sediment", Ph.D. Thesis, Oxford University.
  8. Gibson, R. E., England, G. L., and Hussey, M. J. L. (1967), "The theory of one-dimensional consolidation of saturated clay I: finite non-linear consolidation of thin homogeneous layers", Geotechnique, Vol.17, No.3, pp.261-273. https://doi.org/10.1680/geot.1967.17.3.261
  9. Imai, G. (1979), "Development of a new consolidation test procedure using seepage force", Journal of soil and foundation, Vol.19, No.3, pp.45-60.
  10. Imai, G. (1981), "Experimental studies on sedimentation mechanism and sediment formation of clay materials", Journal of Soil and Foundation, Vol.21, No.1, pp.7-20. https://doi.org/10.3208/sandf1972.21.7
  11. Jackson, P. D., Smith, D. T., and Stanford, P. N. (1978), "Resistivityporosity- particle shape relationships for marine sands", Geophysics, Vol.43, No.6, pp.1250-1268. https://doi.org/10.1190/1.1440891
  12. Kim, H. J. and Oh, G. Y. (1999), "A study on the self-weight consolidation procedure of very soft ground reclaimed by dreedging clayey soil", Journal of Korean Geotechnical Society, Vol.15, No. 2, pp.129-138.
  13. Kim, J. H., Yoon, H. K., and Lee, J. S. (2011), "Void ratio estimation of soft soils using electrical resistivity cone probe", Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol.137, No.1, pp.86-93. https://doi.org/10.1061/(ASCE)GT.1943-5606.0000405
  14. Klein, K. and Santamarina, J. C. (2005), "Soft sediments: wavebased characterization", International journal of geomechanics, Vol. 5, No.2, pp.147-157. https://doi.org/10.1061/(ASCE)1532-3641(2005)5:2(147)
  15. Klein, K. and Simon, D. (2006), "Effect of specimen composition on the strength development in cemented paste backfill", Canadian geotechnical journal, Vol.43, No.3, pp.310-324. https://doi.org/10.1139/t06-005
  16. Kondo, F. and Torrance, J. K. (2005), "Effects of smectite, salinity and water content on sedimentation and self-weight consolidation of thoroughly disturbed soft marine clay", Paddy and Water Environment, Vol.3, No.3, pp.155-164. https://doi.org/10.1007/s10333-005-0012-8
  17. Lide, D. R. (2007), "CRC handbook of chemistry and physics", 88th edn, 2007-2008", CRC press, Talyor and Francis.
  18. Lee, J. S. and Santamarina, J. C. (2005), "Bender elements: performance and signal interpretation", Journal of Geotechnical and geoenvironmental engineering, Vol.131, No.9, pp.1063-1070. https://doi.org/10.1061/(ASCE)1090-0241(2005)131:9(1063)
  19. Lee, W. J., Shin, D. H., Yoon, H. K., and Lee, J. S. (2009), "Microcone penetrometer for more concise subsurface layer detection", Geotechnical Testing Journal, Vol.32, No.4, pp.358-364.
  20. Martinez, B. C., DeJong, J. T., Ginn, T. R., Montoya, B. M., Barkouki, T. H., Hunt, C., Tanyu, B., and Major, D. (2013), "Experimental optimization of microbial-induced carbonate precipitation for soil improvement", Journal of Geotechnical and Geoenvironmental Engineering, Vol.139, No.4, pp.587-598. https://doi.org/10.1061/(ASCE)GT.1943-5606.0000787
  21. McDermott, I. R. (1997), "The use of shear wave transmission as a non-destructive tool to assess soft soil stiffness in dredging applications", Geological Society, London, Engineering Geology Special Publications, Vol.12, No.1, pp.347-353. https://doi.org/10.1144/GSL.ENG.1997.012.01.32
  22. McRoberts, E. C. and Nixon, J. F. (1976), "A theory of soil sedimentation", Canadian Geotechnical Journal, Vol.13, No.3, pp. 294-310. https://doi.org/10.1139/t76-031
  23. Mikasa, M. (1963), "The consolidation of soft clay-a new consolidation theory and its application", Tokyo Kajima Shupan-kai, pp.56-86.
  24. Miura, K., Yoshida, N., and Kim, Y. S. (2001), "Frequency dependent property of waves in saturated soil, Soils and Foundations, Vol.41, No.2, pp.1-19.
  25. Morris, P. H. (2002), "Analytical solutions of linear finite-strain one-dimentional consolidation", Journal of geotechnical and geoenvironmental engineering, ASCE, Vol.128, No.4, pp.319-326. https://doi.org/10.1061/(ASCE)1090-0241(2002)128:4(319)
  26. Pane, V. (1985), "Sedimentation and consolidation of clays", Ph.D. Thesis, boulder, University of Coloado.
  27. Salem, H. S. and Chilingarian, G. V. (1999), "The cemention factor of Archie's equation for shaly sandstone reservoirs", Journal of Petroleum Science and Engineering, Vol.23, No.2, pp.83-93. https://doi.org/10.1016/S0920-4105(99)00009-1
  28. Stark, T. D., Choi, H., and Schroeder, P. R. (2005a), "Settlement of dredged and contaminated material placement areas, I: theory and use of primary consolidation, secondary compression, and desiccation of dredged fill", Journal of Waterway, Port, Coastal and Ocean Engineering, ASCE, Vol.131, No.2, pp.43-51. https://doi.org/10.1061/(ASCE)0733-950X(2005)131:2(43)
  29. Stark, T. D., Choi, H., and Schroeder, P. R. (2005b), "Settlement of dredged and contaminated material placement areas, II: primary consolidation, secondary compression, and desiccation of dredged fill input parameters", Journal of Waterway, Port, Coastal and Ocean Engineering, ASCE, Vol.131, No.2, pp.52-61. https://doi.org/10.1061/(ASCE)0733-950X(2005)131:2(52)
  30. Tan, T. S., Yong, K. Y., Leong, E. C., and Lee, S. L. (1990), "Behavior of clay slurry", Soils and Foundations, Vol.30, No.4, pp.105-118. https://doi.org/10.3208/sandf1972.30.4_105
  31. Terzaghi, K. and Peck, R. B. (1943), "Soil mechanics in engineering practices", John Wiley and Sons, New York.
  32. Titi, H. H., Mohammad, L. N., and Tumay, M.T. (2000), "Miniature cone penetration tests in soft and stiff clays, "Geotechnical Testing Journal, ASTM, Vol.23, No.4, pp.432-443. https://doi.org/10.1520/GTJ11064J
  33. Umehara, Y. and Zen, K. (1982), "Consolidation characteristics of dredged marine bottom sediments with high water contents", Journal of Japanese Society of Soil Mechanics and Foundation Engineering, Vol.22, No.2, pp.40-54.
  34. Wang, Y. H. and Dong, X. (2008), "Complementary wave-based characterizations of sedimentation processes", Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol.134, No.1, pp.47-56. https://doi.org/10.1061/(ASCE)1090-0241(2008)134:1(47)
  35. Yano, K. (1985), "Properties of very soft ground reclaimed by dredged marine clay and their prediction", Journal of Japan Society of Civil Engineering, Vol.364, No.III-4, pp.1-4.
  36. Yoon, H. K. and Lee, J. S. (2010), "Field velocity resistivity probe for estimation stiffness and void ratio", Journal of Soil Dynamics and Earthquake Engineering, Vol.30, No.12, pp.1540-1549. https://doi.org/10.1016/j.soildyn.2010.07.008
  37. Znidarcic, D. (1999), "Predicting the behavior of disposed dredging soils", Geotechnical Engineering for Transportation Infrastructure, Proceedings of the 12th European Conference on Soil Mechanics and Geotechnical Engineering, Vol.2, pp.877-886.