Journal of the Korean GEO-environmental Society (한국지반환경공학회 논문집)

Korean Geo-Environmental Society (한국지반환경공학회)
권호 표지
DOI QR코드

DOI QR Code

Analysis of Liquefied Layer Activities Considering Erosion and Sedimentation of Debris Flow

토석류의 침식 및 퇴적을 고려한 유동층의 거동 분석

  • Kim, Sungduk (School of Civil Engineering, Chungbuk National University) ;
  • Lee, Hojin (School of Civil Engineering, Chungbuk National University)
  • Received : 2019.02.28
  • Accepted : 2019.03.22
  • Published : 2019.04.01
Download PDF
⟨ Previous Next ⟩

Abstract

Heavy rainfall is in causing debris flow by recent climate change and causes much damage in the downstream. The debris flow from the mountainous area runs to the downstream, repeating sedimentation and erosion, and appears as a fluidized soil-water mixture. Continuity equation and momentum equation were applied to analyze the debris flow with strong mobility, and the sedimentation and erosion velocity with fine particle fractions were also applied. This study is to analyze the behavior of debris flow at the downstream end for the variation of the amount of sediments can occur in the upstream of the mountain. Analysis of sediment volume concentration at the downstream end of the channel due to the variance of the length of pavement of the granulated soils resulted in the higher the supply flow discharge and the longer the length of pavement, the greater the difference in the level of sediment concentration and the earlier the point of occurrence of the inflection point. The results of this study will provide good information for determining the erosion-sedimentation velocity rate which can detect erosion and sedimentation on steep slopes.

최근의 기후변화는 산지가 많은 우리나라에서 토석류를 발생시켜 하류에 많은 재난을 야기하였다. 산지에서 발생한 토석류는 퇴적과 침식을 반복하며 하류로 이동하고, 유동화된 토사-물 혼합물 형태로 나타난다. 이처럼 강한 운동성의 토석류를 해석하기 위하여 연속방정식 및 운동량 방정식을 적용하였고, 퇴적 및 침식에 관한 속도식은 세립사가 포한된 수정형을 적용하였다. 본 연구는 산지 상류부에서 발생 가능한 퇴적토사량의 변화에 대한 하류부에서의 토석류 거동을 분석한 것이다. 조립토사의 포설 길이 변화에 따른 수로 하류단에서 토사체적농도를 분석해 보면, 공급유량이 많고 포설길이가 길수록 토사농도의 고저차가 크게 나타났고, 변곡점 발생 시점도 빨라진 것을 알 수 있다. 본 연구의 결과는 급경사의 비탈사면에서의 침식 및 퇴적 가능 여부를 알 수 있는 침식-퇴적 속도를 판단하여 토석류 재해에 대한 대책을 세우는 데 좋은 정보를 제공할 것이다.

Keywords

HJHGC7_2019_v20n4_23_f0001.png 이미지

Fig. 1. Schematic design for numerical experiment of debris flow

HJHGC7_2019_v20n4_23_f0002.png 이미지

Fig. 2. Sediment concentration at the downstream end varying the sediment supply for channel for θ=16° and q=600 cm3/sec

HJHGC7_2019_v20n4_23_f0003.png 이미지

Fig. 3. Sediment concentration at the downstream end varying the sediment supply for channel for θ=16° and q=600 cm3/sec

HJHGC7_2019_v20n4_23_f0004.png 이미지

Fig. 4. Sediment concentration at the downstream end varying the sediment supply for channel for θ=16° and q=1,000 cm3/sec

HJHGC7_2019_v20n4_23_f0005.png 이미지

Fig. 5. Sediment concentration at the downstream end varying the sediment supply for channel for θ=20° and q=1,000 cm3/sec

HJHGC7_2019_v20n4_23_f0006.png 이미지

Fig. 6. Sediment concentration on the channel varying water supply with fine sediment fraction for θ=14°

HJHGC7_2019_v20n4_23_f0007.png 이미지

Fig. 7. The height of erosion and sedimentation on the channel varying water supply for θ=20°

References

  1. Armanini, A., Fraccarollo, L. and Rosatti, G. (2009), Two-dimensional simulation of debris flows in erodible channels, Computers & Geosciences, Vol. 35, pp. 993-1006. https://doi.org/10.1016/j.cageo.2007.11.008
  2. Bagnold, R. A. (1954), Experiments on a gravity-free dispersion of large solid spheres in a Newtonian fluid under shear. Proc. R.S. London, Ser. A225, 49-63.
  3. Blair, T. C. and McPherson, J. G. (1994), Alluvial fan processes and forms, in Abrahams, A. D., and Parsons, A. J., eds., Geomorphology of desert environments, London, Chapman and Hall, pp. 354-402.
  4. Choi, J. H. and Jun, K. W. (2015), Analysis experiment of reduction effect of trees miniature model on debris flow-focusing on the study on making of trees miniature model-, Journal of Korean Society of Environmental Technology, Vol. 16, No. 22, pp. 177-185 (In Korean).
  5. DeGraff, J. (1994), The geomorphology of some debris flows in the Southern Sierra Nevada, California, Geomorphology, Vol. 10, pp. 231-252. https://doi.org/10.1016/0169-555X(94)90019-1
  6. Egashira, S., Miyamoto, K. and Itoh, T. (1997), Constitutive equation of debris flow and their applicability, 1st International Conference on Debris-Flow Hazards Mitigation, ASCE, pp. 340-349.
  7. Gori, P. L. and Burton, W. C. (1996), Debris flow hazards in the Blue Ridge of Virginia, U.S. Geological Survey Fact Sheet, pp. 159-96.
  8. Kim, C. K., Bak, G. J., Kim, J. C., Song, S. Y. and Yun, J. M. (2013), Prediction of slope hazard probability around express way using decision tree model, Journal of Korean Geosynthetics Society, Vo. 12, No. 2, pp. 67-74 (In Korean). https://doi.org/10.12814/jkgss.2013.12.2.067
  9. Kim, S. D. and Lee, H. J. (2015), Assessment of risk due to debris flow and its application to a marine environment, Marine Georesources and Geotechnology, Vol. 33, No. 6, 572-578. https://doi.org/10.1080/1064119X.2014.954181
  10. Kim, S. D., Lee, H. S., Jun, B. H. and Jun, K. W. (2016), The analysis of liquefied-layer of debris flow on the various slope of parallel steep under the environmental soil condition, Journal of Korean Society of Environmental Technology, Vol. 17, No. 3, pp. 266-274 (In Korean).
  11. Kim, S. D., Yoon, I. R., Oh, S. W., Lee, H. J. and Bae, W. S. (2012), Numerical simulation for behavior of eebris flow according to the variances of slope angle, Journal of the Korean Geo-Environmental Society, Vol. 13, No. 6, pp. 59-66 (In Korean).
  12. Nakagawa, H., Satofuka, Y. and Takahama, J. (2002), Water induced hazard-.I, Sub Text Book, M. Sc. in Water Resources Engineering, Institute of Engineering, Nepal, pp. 1-40.
  13. Schwab, W. C., Lee, H. J., Twichell, D. C., Locat, J., Nelson, C. H., McArthur, W. G. and Kenyon, N. H. (1996), Sediment mass-flow processes on a depositional lobe, Outer Mississippi Fan, Journal of Sedimentary Research, Vol. 66, pp. 916-927.
  14. Takahashi, T., Nakagawa, H., Harada, T. and Yamashiki, Y. (1992), Routing debris flows with particle segregation, Journal of Hydraulic Engineering, Vol. 118, No. 11, pp. 1490-1507. https://doi.org/10.1061/(ASCE)0733-9429(1992)118:11(1490)