Experiment of Channelization Due to Seepage Erosion

Abstract

ABSTRACT:We have investigated channelization due to seepage erosion using two sizes of coarse sand (d50 = 0.86 and 0.56 mm), two chamber slopes (S = 0 and 3%) and three upstream water depths (H = 15, 17 and 19 cm). Water was fed at the far upstream end of a sand layer, and a small incipient channel was made at the center of the downstream scarp. Thus, groundwater flow converged into the central channel, promoted erosion and caused the development in both width and length. At the beginning, the retreat rates of channel heads were rapid but decreased after a while. A higher H induced a faster retreat and a larger size of the center channel. In the experiments with S = 0%, channel head bifurcation was always observed for d50 = 0.86 mm but not d50 = 0.56 mm. Thus, not only the characteristics of groundwater flow field soil properties but the sediment properties also affect the shapes of evolving channels. For S = 3%, however, bifurcation was only found in the experiment with d50 = 0.86 mm and H = 15 cm. It implies that H also controls bifurcation. In addition, new channels were initiated at the downstream scarp when S = 3%. An increase in the streamwise discharge due to a steeper slope may weaken the convergence of the groundwater flow into the center channel. Using the concept of network circularity, we can divide the channel development of our experiments into the initiation and extension phases.

Laboratory Experiment of Channel Head Bifurcation by Radial Overland Flow

“…The transition between the unchannelization phase and the initiation phase is then expected to be the time of incipient channelization according to the theory by [3]. The latest experimental, numerical and theoretical studies [12]- [14] show that bifurcation generated by overland flow and seepage erosion should be investigated by process-based approaches. Thus, better flow models and erosion functions may be necessary and important for future research.…”

Experimental Study on Measurement of Drag Coefficient of Sandy Soil Nonlinear Vadose

“…When the seepage force is too large, relative movement between soil particles and even overall movement of the soil body will occur, and seepage deformation or even destruction will occur [1,2], causing damage to dams and foundation pits [3,4], slope instability [5,6], ground uplift, and other issues [7,8]. aisiam et al [9] believed that after seepage erosion, with the continuous movement of fine particles, some pores in the sand may be blocked or enlarged, which will result in the change of the soil permeability coefficient. Moffat and Fannin [10] proposed that seepage erosion causes the permeability coefficient of soil to increase from upstream to downstream.…”