소형 수로실험을 통한 토석류 유동속도 추정식 평가 = Examining Velocity Estimation Equations of Debris Flow Using Small-scaled Flume Experiments

국문 초록 (Abstract)

토석류는 빠른 속도와 넓은 퇴적 범위 등으로 인명 및 재산 피해를 야기하는 산지토사재해이다. 토석류 피해 저감 을 목적으로 효과적인 사방 구조물을 설계하기 위해서는 토석류의 충격력을 정확하게 산정하여야 한다. 토석류의 유동속 도는 토석류 충격력을 추정하는데 중요한 요인이다. 따라서 이 연구에서는 소형 수로실험을 통해 수로경사 및 시료 조건 에 따른 토석류의 유동특성을 실험적으로 분석하고, 토석류 유동속도 추정식의 유동저항계수를 추정하였다. 유동속도는 수로의 경사조건 및 시료의 점성조건에 유의한 변화를 보였다. 유동깊이는 수로경사에 대해서 유의한 차이를 보였으나 시 료의 점성변화에 대해서는 유의한 변화를 보이지 않았다. 유동저항계수를 계산하여 분석한 결과, Voellmy flow 모형의 Chezy 상수(C1)가 상대적으로 수로실험 결과를 잘 재현하였다. 또한, 실제 토석류 사례와의 비교 결과, 유동깊이에 관계 없이 일정한 값(20.19 m-1/2 s-1)을 보였다. 따라서, C1은 다양한 발생규모의 토석류에 대한 유동속도 추정에 잘 활용될 수 있을 것으로 보인다.

다국어 초록 (Multilingual Abstract)

With its rapid velocity and wide deposition, debris flow is a natural disaster that causes loss of human life and destruction of facility. To design effective debris barriers, impact force of debris flow should be first considered. Debris flow velocity is one of the key features to estimate the impact force of debris flow. In this study, we conducted small-scale flume experiments to analyze flow characteristics of debris flow, and determine flow resistance coefficients with different slope gradients and sediment mixtures. Flow velocity significantly varied with flume slope and mixture type. Debris flow depth decreased as slope increased, but difference in depth between sediment mixtures was not significant. Among flow resistance coefficients, Chezy coefficient (C1) showed not only relatively highest goodness of fit, but also constant value (20.19 m -1/2 s -1 ) regardless the scale of debris flow events. The overall results suggested that C1 can be most appropriately used to estimate flow velocity, the key factor of assessing impact force, in wide range of debris flow scale.

참고문헌 (Reference)

1 Koo, R. C. H., "Velocity attenuation of debris flows and a new momentum-based load model for rigid barriers" 14 (14): 617-629, 2016

2 Iverson, R. M., "The perfect debris flow? Aggregated results from 28large-scale experiments" 115 : F03005-, 2010

3 Koch, T, "Testing various constitutive equations for debris flow modelling" 248 : 249-258, 1998

4 Iverson, R. M, "Scaling and design of landslide and debris-flow experiments" 244 : 9-20, 2015

5 Hungr, O., "Quantitative analysis of debris torrent hazards for design of remedial measures" 21 (21): 663-677, 1984

6 Bugnion, L., "Measurements of hillslope debris flow impact pressure on obstacles" 9 (9): 179-187, 2012

7 Scheidl, C., "Landslide Science and Practice" Springer 221-229, 2013

8 Pierson, T. C., "Initiation and flow behavior of the 1980Pine Creek and Muddy river lahars, Mount St. Helens, Washington" 96 (96): 1056-1069, 1985

9 유송, "Flow and deposition characteristics of sediment mixture in debris flow flume experiments" 한국산림과학회 13 (13): 61-65, 2017

10 Parsons, J. D., "Experimental study of the grain‐flow, fluid‐mud transition in debris flows" 109 (109): 427-447, 2001

11 Rickenmann, D, "Empirical relationships for debris flows" 19 (19): 47-77, 1999

12 Jakob, M., "Debris-flow hazards and related phenomena" Springer 736-, 2005

13 Takahashi, T, "Debris flow: mechanics, prediction and countermeasures" CRC Press/ Balkema 551-, 2014

14 Proske, D, "Debris flow impact estimation for breakers" 5 (5): 143-155, 2011

15 Takahashi, T, "Debris flow" 13 (13): 57-77, 1981

16 Fairfield, G., "Assessing the dynamic influences of slope angle and sediment composition on debris flow behaviour:An experimental approach" Durham University 2011

17 Hungr, O, "Analysis of debris flow surges using the theory of uniformly progressive flow" 25 (25): 483-495, 2000

18 Scheidl, C., "Analysing debris-flow impact models, based on a small scale modelling approach" 34 (34): 121-140, 2013

19 Prochaska, A. B., "A study of methods to estimate debris flow velocity" 5 (5): 431-444, 2008

20 Hungr, O., "A review of the classification of landslides of the flow type" 7 (7): 221-238, 2001

21 García Aragón, J. A, "A hydraulic shear stress model for rapid, highly concentrated flow" 34 (34): 589-596, 1996