노후화된 균일형 저수지 제체의 월류모형실험과 3차원 침투특성

Overtopping Model Experiments and 3-D Seepage Characteristics of the Embankment of Deteriorated Homogeneous Reservoirs

Abstract

In this study, an overtopping model experiments and three dimensional seepage characteristics at the deteriorated homogeneous reservoirs were performed to investigate the behavior of failure for embankment and spillway transitional zone due to overtopping. The failure pattern, pore water pressure, earth pressure and settlement by overtopping were compared and analyzed. The pattern of the failure by overtopping was gradually enlarged towards reservoirs crest from the spillway transition zone at initial stage. In the rapid stage and peak stage, the width and depth of failure gradually increased, and the pattern of the failure appeared irregular and several direction of the erosion. In the early stage, the pore water pressure at spillway transitional zone was more affected as its variation and failure width increased. In the peak stage, the pore water pressure was significantly increased in all locations due to the influence of seepage. The earth pressure increased gradually according to overtopping stage. The pore pressure by the numerical analysis was larger than the experimental value, and the analysis was more likely to increase steadily without any apparent variation. The horizontal and vertical displacements were the largest at the toe of slope and at the top of the dam crest, respectively. The results of this displacement distribution can be applied as a basis for determining the position of reinforcement at the downstream slope and the crest. The collapse in the overtopping stage began with erosion of the most vulnerable parts of the dam crest, and the embankment was completely collapsed as the overtopping stage increased.

Fig. 1 Laboratory model test and location of monitoring

Fig. 2 Failure shape of downstream slope by overtopping stage

Fig. 3 Variation of pore water pressure and earth pressure

Fig. 4 Variation of settlement

Fig. 6 Distribution of phreatic line and pore water pressure

Fig. 7 Variations of pore water pressure by analysis condition

Fig. 8 Distribution of horizontal(x-axis) and vertical(z-axis) displacement

Fig. 9 Distribution of maximum horizontal(x-axis) and vertical(z-axis) displacement by overtopping stage

Fig. 10 Failure shape by overtopping stage

Fig. 5 Cross section of the 3-D analysis

Table 1 Geotechnical properties of materials used

Table 2 Analysis condition