Experimental Study on Erosional Behaviour of Fine-Grained Sediments

Choi, In Ho; Kim, Jong Woo

Journal of the Korean Society of Hazard Mitigation 2014;14(3):291-298.
Published online June 30, 2014.

미립자 퇴적물의 침식거동에 관한 실험연구

최인호, 김종우

Experimental Study on Erosional Behaviour of Fine-Grained Sediments

In Ho Choi, Jong Woo Kim

Abstract

Experiments on erosional behaviour of fine-grained sediments were carried out in a small annular flume with increasing the initial concentration, pH value and the consolidation time. Quartz was used as sediment material. The suspended concentrations were measured using a CCD Camera. Results indicate that the solution pH and consolidation time significantly affect the erosion rate of quartz. Under acid conditions(=pH4.2), the erosion rate of quartz was slowly increased, whereas in a neutral pH(=pH6.8), the erosion rate was rapidly increased. The erosion rate of quartz decreased at increasing consolidation time in distilled water. However, the erosion rate of the initial concentration of 7 g/L was higher than that of the initial concentration of 1 g/L. Thus, the critical shear stress for erosion ranged from approximately 0.013 to $0.035N/m^2$ under increasing the initial concentration, pH value and the consolidation time.

Key Words: Erosion rate; Critical shear stress; Annular flume; Suspended concentration; Consolidation time

요지

미립자 퇴적물의 침식거동에 관한 실험은 초기농도, pH와 응고시간의 증가에 따라 소형환형수조에서 실시되었다. 석영이 실험재료로 사용되었다. 부유농도는 CCD Camera를 사용하여 측정되었다. 연구결과에서 석영의 침식률이 pH와 응고시간에 크게 영향을 받는 사실을 볼 수 있다. 중성(=pH6.8)일 경우 석영의 침식률이 급속히 증가되는 반면 산성(=pH4.2)일 경우 석영의 침식률은 서서히 증가되었다. 석영의 침식률은 증류수에서 응고시간이 증가할수록 감소하였다. 그러나 초기농도 7 g/L일 경우 침식률은 초기농도 1 g/L보다 높게 나타난다. 결과적으로 초기농도, pH 및 응고시간의 증가에 따른 석영의 침식한계전단응력의 범위는 약 $0.013{sim}0.035N/m^2$이다.

핵심용어: 침식률; 한계전단응력; 환형수조; 부유농도; 응고시간