Influence of water level fluctuation on phreatic line in silty soil model slope

The water level fluctuation may affect the phreatic line in the waterfront soil slopes. In order to investigate the influence, three slope models were made using the silty soil. Four testing schemes for rising water level and three for lowering water level were done. The testing results indicated that such factors as the horizontal distance from the piezometer tube to the intersection of the slope surface and water level, the saturated state of the soil mass, and the rate of the water level fluctuation, might affect the changing rate of the water table in the piezometer tube. The comparison of the results obtained from the present approach with [Zhang Y.-Y. and Hu, X.-W., 2007. Calculation of saturation line of groundwater under reservoir water table uniform rising. Hydrogeology and Engineering Geology, 2007(5): 46–49. (in Chinese)] indicated that the works of Zhang and Hu (2007) may overestimate the elevation of the phreatic line under uniform rising conditions. The comparison of the results from the present approach with [Zheng, Y.-R, Shi, W.-M., and Kong W.-X., 2004. Calculation of seepage forces and phreatic surface under drawdown conditions. Chinese Journal of Rock Mechanics and Engineering, 23(18): 3203-3210. (In Chinese)] indicated that the works of Zheng et al. (2004) might estimate reasonably the elevation of the phreatic line under uniform lowering conditions, but when the lowering rate of the water level is very large, the works of Zheng et al. (2004) may underestimate the phreatic line.