Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Debris Flow Mobility: A Comparison of Weathered Soils and Clay-rich Soils

풍화토와 점성토 위주의 토석류 거동과 유동특성

  • Received : 2012.07.10
  • Accepted : 2012.12.17
  • Published : 2013.01.31
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Abstract

The risks of debris flows caused by climate change have increased significantly around the world. Recently, landslide disaster prevention technology is more focused on the failure and post-failure dynamics to mitigate the hazards in flow-prone area. In particular, we should define the soil strength and flow characteristics to estimate the debris flow mobility in the mountainous regions in Korea. To do so, we selected known ancient landslides area: Inje, Pohang and Sangju debris flows. Firstly we measured physical and mechanical properties: liquidity index and undrained shear strength by fall cone penetrometer. From the test results, we found that there is a possible relationship between liquidity index and undrained shear strength, $C_{ur}=(1.2/I_L)^{3.3}$, in the selected areas, even though they were different in geological compositions. Assuming that the yield stress is equal to the undrained shear strength at the initiation of sliding, we examined the flow characteristics of weathered soils in Korea. When liquidity index is given as 1, 1.5 and 3.0, the debris flow motion of weathered soils is compared with that of mud-rich sediments, which are known as low-activity clays. At $I_L=1$, it seems that debris flow could reach approximately 250m after 5 minutes. As liquidity index increased from 1 to 3, the debris flow propagation of weathered soils is twice than that of low-activity clays. It may be due to the fact that soil masses mixed with the ambient water and then highly fragmented during flow, thereby leading to the high mobility. The results may help to predict the debris flow propagation and to develop disaster prevention technology at similar geological settings, especially for the weathered soils, in Korea.

기후변화에 따른 토석류 발생과 그로 인한 피해가 세계적으로 증가 추세에 있다. 토석류 연구는 역학적 관점에서 파괴 후(post-failure) 거동에 해당하며 지반강도와 유동특성을 분석함으로써 특성화할 수 있다. 본 연구는 국내의 토석류 발생지역인 상주(화강암 풍화토), 인제(편마암 풍화토), 포항(이암 및 셰일) 지역을 대상으로 지반의 물성-전단강도 상관관계와 토석류의 유동특성을 평가하였다. 본 연구지역을 대상으로 스웨덴 낙하 콘(Swedish Fall cone) 시험장치를 이용하여 지반의 물성 및 지반강도 사이에 일정한 상관관계가 있음을 밝혔다. 실험결과에 따르면, 인제, 상주, 포항지역에서 채취된 시료에 대해 액성지수(IL)와 비배수 전단강도($C_{ur}$) 사이에 $C_{ur}=(1.2/I_L)^{3.3}$의 관계식이 성립한다. 토석류 흐름을 지배하는 항복응력은 재성형 비배수 전단강도에 상응하는 것으로 간주하고, Bingham 모델과 액성지수-항복응력 관계식을 이용하여 토석류의 유동성을 조사하였다. 유동해석은 국내 풍화토와 낮은 활성점토를 구분하여 적용하였다. 이때 액성지수는 액성한계를 기준으로 $I_L=1$, 1.5, 3.0으로 구분하여 비교분석하였다. 동일한 액성지수($I_L=1$)에 대해, 토석류의 발생 5분 경과 후 최대 이동거리는 250m에 다다른다. 액성지수가 3으로 증가 될 경우, 토석류의 이동거리를 5분까지 살펴본 결과, 국내 풍화토는 낮은 활성점토에 비해 2배 이상 큰 유동성이 있음을 알 수 있었다. 본 유동성 평가기술은 토석류 피해저감기술 전략수립에 활용할 수 있을 것으로 기대된다.

Keywords

References

  1. Bardou, E., Bowen, P., Boivin, P., and Banfill, P. (2006). "Impact of small amounts of swelling clays on the physical properties of debris flow-like granular materials: Implications for the study of alpine debris flow", Earth surface processes and landforms, Vol. 32, pp.698-710.
  2. Barnes, H. A. (1999). "The yield stress-a review or '${\pi}{\alpha}{\nu}{\tau}$ ${\rho}{\varepsilon}{\iota}'-everything flows$?", Journal of Non-Newtonian Fluid Mechanics, Vol.81, pp.133-178. https://doi.org/10.1016/S0377-0257(98)00094-9
  3. Boivin, P., Bardou, E., and Pfeifer, H. R. (2004), Role and behaviour of clay minerals in alpine debris flows, EosTrans. AGU, 85, Fall Meet. Suppl., Abstract, H43G-03.
  4. CAN/BNQ, 1986a, Soil-determination of sensitivity of cohesive soils by Swedish fall cone penetrometer method, Canadian Standards Association and Bureau de normalization du Quebec, CAN/BNQ 2501-110-M-86.
  5. CAN/BNQ, 1986b, Soil-determination of liquid limit by the Swedish fall cone penetrometer method and determination of plastic limit, Canadian Standards Association and Bureau de normalization du Quebec, CAN/BNQ 2501-092-M-86.
  6. Coussot, P., Nguyen, G. D., Huynh, H. T., and Bonn, D. (2002), "Viscosity bifurcation in thixotropic, yielding fluids", Journal of Rheology, Vol.46, pp.573-589. https://doi.org/10.1122/1.1459447
  7. Coussot, P. and Piau, J.-M. (1994), "On the behavior of fine mud suspensions", Rheologica Acta", Vol.33, pp.175-184. https://doi.org/10.1007/BF00437302
  8. Elverhoi, A., Issler, D., De Blasio, F. V., Ilstad, T., Harbitz, C. B., and Gauer, P. (2005), "Emerging insights into the dynamics of submarine debris flows", Natural Hazards and Earth System Sciences, Vol.5, pp.633-648. https://doi.org/10.5194/nhess-5-633-2005
  9. Hansbo, S. (1957), "A new approach to the determination of the shear strength of clay by the fall-cone test", Royal Swedish Geotechnical Institute, Proceedings, Vol.14, pp.5-47.
  10. Hungr, O. (1995), "A model for the runout analysis of rapid flow slides, debris flows and avalanches", Canadian Geotechnical Journal, Vol.32, pp.610-623. https://doi.org/10.1139/t95-063
  11. Hungr, O., Evans, S. G., Bovis, M., and Hutchinson, J. N. (2001), "Review of the classification of landslides of the flow type", Environmental and Engineering Geoscience, VII, pp.221-238.
  12. Hungr, O., McDougall, S., and Bovis, M. (2005), "Entrainment of material by debris flows", In: Debris-flow Hazards and Related Phenomena, M. Jakob and O. Hungr (eds), Praxis, Springer Berlin Heidelberg, pp.135-158.
  13. Hungr, O. (2009), "Numerical modelling of the motion of rapid, flow-like landslides for hazard assessment", KSCE Journal of Civil Engineering, Vol.13(4), pp.281-287. https://doi.org/10.1007/s12205-009-0281-7
  14. Hungr, O., Leroueil, S., and Picarelli, L. (2012), "Varnes classification of landslide types, an update, Landslides and engineered slopes: Protecting society through improved understanding", Eberhardt et al. (eds.), Taylor & Francis Group, London, pp.47-58.
  15. Huynh, H. T., Roussel, N., and Coussot, P. (2005), "Aging and free surface flow of a thixotropic fluid", Physics of Fluids, Vol.17, pp.033101. https://doi.org/10.1063/1.1844911
  16. Imran, J., Parker, G., and Pirmez, C. (1999), "A nonlinear model of flow in meandering submarine and subaerial channels", Journal of Fluid Mechanics, Vol.400, pp.295-331. https://doi.org/10.1017/S0022112099006515
  17. Imran, J., Harff, P., and Parker, G. (2001), "A numerical model of submarine debris flows with graphical user interface", Computers & Geosciences, Vol.27(6), pp.717-729. https://doi.org/10.1016/S0098-3004(00)00124-2
  18. Iverson, R. M. (1997), "The physics of debris flows", Reviews of Geophysics, Vol.35(3), pp.245-296. https://doi.org/10.1029/97RG00426
  19. Jeong, S. W., Locat, J., and Leroueil, S. (2004), "A preliminary analysis of the rheological transformation due to water infiltration as a mechanism for high mobility of submarine mass movements", 57th Canadian Geotechnical Conference, Quebec, Session 7G, pp.15-22.
  20. Jeong, S. W. (2006), Influence of physico-chemical characteristics of fine-grained sediments on their rheological behavior, PhD Thesis, Laval University, Quebec, Canada.
  21. Jeong, S. W., Leroueil, S., and Locat, J. (2009), "Applicability of power law for describing the rheology of soils of different origins and characteristics", Canadian Geotechnical Journal, Vol.46(9), pp.1011-1023. https://doi.org/10.1139/T09-031
  22. Jeong, S. W., Locat, J., Leroueil, S., and Malet, J.-P. (2010), "Rheological properties of fine-grained sediments: the roles of texture and mineralogy", Canadian Geotechnical Journal, Vol.47(10), pp.1085-1100. https://doi.org/10.1139/T10-012
  23. Jeong, S. W. (2010), "Grain size dependent rheology on the mobility of debris flows", Geosciences Journal, Vol.14(4), pp.359-369. https://doi.org/10.1007/s12303-010-0036-y
  24. Jeong, S. W. (2011), "Rheological models for describing fine-laden debris flows: grain-size effect", Journal of Korean Geotechnical Society, Vol.27, No. 6, pp.49-61. (Korean). https://doi.org/10.7843/kgs.2011.27.6.049
  25. Jeong, S. W., Locat, J., and Leroueil, S. (2012), "The effect of salinity and shear history on rheological characteristics of illite-rich and Na-montmorillonite-rich clay", Clays and Clay Minerals, Vol.60(2), pp.108-120. https://doi.org/10.1346/CCMN.2012.0600202
  26. Jeong, S. W., Locat, J., and Leroueil, S. (2012), "Fluidization process in submarine landslides: physical and numerical considerations", Marine Georesources & Geotechnology, In press.
  27. Johnson, A. M., Rodine, J. R. (1984), "Debris flows". Slope Instability. In: Brunsden, D., and Prior, D. B. (eds.), Wiley, Chichester, pp.257-361.
  28. Khaldoun, A., Moller, P., Fall, A., Wegdam, G., De Leeuw, B., Meheust, Y., Fossum J. O., and Bonn, D. (2009), "Quick clay and landslides of clayey soils", Physical Review Letters, Vol.103, 188301. https://doi.org/10.1103/PhysRevLett.103.188301
  29. Kim, K. S., Song, Y. S., Cho, Y. C., Kim, W. Y., and Jeong, G. C. (2006), "Characteristics of rainfall and landslides according to the Geological condition", The Journal of Engineering Geology, Vol.16, pp.201-204. (Korean).
  30. Korea Institute of Geoscience and Mineral Resources (2003), Study on landslide hazard prediction, Ministry of Knowledge Economy, 00-J-ND-01-B-15, 339p. (Korean)
  31. Korea Institute of Geoscience and Mineral Resources (2009), Development of practical technologies for countermeasures for hazards in steep slope and abandoned mine areas, Ministry of Knowledge Economy, GP2009-020-2009(1), 315p. (Korean)
  32. Lee, C. J. and Yoo, N. J. (2009), "A study on debris flow landslide disasters and restoration at Inje of Kangwon province, Korea", Journal of the Korean Society of Hazard Mitigation, Vol.9, No. 1, pp.99-10 (Korean).
  33. Leroueil, S., Tavenas F., and LeBihan, J. P. (1983), "Proprietes caracteristiques des argiles de l'est du Canada", Canadian Geotechnical Journal, Vol.20, pp.681-705. https://doi.org/10.1139/t83-076
  34. Leroueil, S. and Le Bihan, J. P. (1996), "Liquid limits and fall cones", Canadian Geotechnical Journal, Vol.33, pp.796-798.
  35. Locat, J. (1997), "Normalized rheological behaviour of fine muds and their flow properties in a pseudoplastic regime", Proc. 1st Int. Conf. on Debris-Flow Hazards Mitigation, San Francisco. ASCE, New York, pp.260-269.
  36. Locat, J. and Demers, D. (1988), "Viscosity, yield stress, remoulded strength, and liquidity index relationships for sensitive clays", Canadian Geotechnical Journal, Vol.25, pp.799-806. https://doi.org/10.1139/t88-088
  37. Locat, J. and Lee, H. J. (2002), "Submarine landslides: advances and challenges", Canadian Geotechnical Journal, Vol.39, pp.193-212. https://doi.org/10.1139/t01-089
  38. Locat, J., Lee, H. J., Locat, P., and Imran, J. (2004), "Numerical analysis of the mobility of the Palos Verdes debris avalanche, California, and its implication for the generation of tsunamis", Marine Geology, Vol.203, pp.269-280. https://doi.org/10.1016/S0025-3227(03)00310-4
  39. Locat, J., Lee, H., ten Brink, U. S., Twichell, D., Geist, E., and Sansoucy, M. (2009), "Geomorphology, stability and mobility of the Currituck slide", Marine Geology, Vol.264, pp.28-40. https://doi.org/10.1016/j.margeo.2008.12.005
  40. Malet, J. P., Remaître, A., Maquaire, O., Ancey, C., and Locat, J. (2003), "Flow susceptibility of heterogeneous marly formations. Implications for torrent hazard control in the Barcelonnette basin (Alpes-de-Haute-Provence, France)", Proceedings of the 3rd International Conference on Debris-Flow Hazards Mitigation, Rickenmann, D., and Chen, C. L. (eds.), Millpress, Rotterdam, pp.351-362.
  41. Papanastasiou, T. C. (1987), "Flows of materials with yield", Journal of Rheology, Vol.31, pp.385-404. https://doi.org/10.1122/1.549926
  42. Park, K. B., Chae, B. G., Kim, K. S., and Park, H. J. (2011), "Analysis of rainfall infiltration velocity for unsaturated soils by an unsaturated soil column test: comparison of weathered gneiss soil and weathered granite soil", Korea Society of Economic and Environmental Geology, Vol.44, pp.71-82. (Korean). https://doi.org/10.9719/EEG.2011.44.1.071
  43. Perret, D., Locat, J., and Martignoni, P. (1996), "Thixotropic behavior during shear of a fine-grained mud from Eastern Canada", Engineering Geology, Vol.43, pp.31-44. https://doi.org/10.1016/0013-7952(96)00031-2
  44. Petley, D. N. (2012), "Landslides and engineered slopes: Protecting society through improved understanding, Landslides and engineered slopes: Protecting society through improved understanding", Eberhardt et al. (eds.), Taylor & Francis Group, London, pp.3-13.
  45. Petrov, R. J., and Rowe, R. K. (1997), "Geosynthetic clay liner (GCL)-chemical compatibility by hydraulic conductivity testing and factors impacting its performance", Canadian Geotechnical Journal, Vol.34, pp.863-885. https://doi.org/10.1139/t97-055
  46. Remaître, A., Malet, J-P., Maquaire, O., Ancey, C., and Locat, J. (2005), "Flow behaviour and runout modelling of a complex debris flow in a clay-shale basin Flow behaviour and runout modeling", Earth surface processes and landforms, Vol.30, pp.479-488. https://doi.org/10.1002/esp.1162
  47. Remaitre, A., van Asch, Th. W. J., Malet, J.-P., and Maquaire, O. (2008), "Influence of check dams on debris-flow run-out intensity", Nat. Hazards Earth Syst. Sci., Vol.8, pp.1403-1416. https://doi.org/10.5194/nhess-8-1403-2008
  48. Terzaghi, K., Peck, R. B., and Mesri, G. (1996), Soil mechanics in engineering practice, 3rd edition. John Wiley & Sons, Inc., NewYork.
  49. Torrance, J. K. (1987), "Shear resistance of remoulded soils by viscometric and fall-cone methods: a comparison for the Canadian sensitive marine clays", Canadian Geotechnical Journal, Vol.24, pp.318-322. https://doi.org/10.1139/t87-037
  50. Wood, D. M. (1985), "Some fall cone tests", Geotechniques, Vol.35(1), pp.64-68. https://doi.org/10.1680/geot.1985.35.1.64

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