Effect of water infiltration through concrete block spillways on the slope stability of earth overflow dams

Abstract

Using wedge-shaped concrete blocks (WSCB) to protect earth dams against overtopping has received much attention in recent years. The aim of this study is to assess the pattern of the infiltrated flow through the WSCBs system into the downstream shell of the earth dam. Moreover, its effects on the downstream slope stability are investigated using the finite-element analysis. A typical zoned earth overflow dam with the WSCB spillway is modelled. For this case study, the effects of depth and duration of overtopping as well as the permeability coefficient of the shell materials on the water infiltration pattern and the downstream safety factor are studied. The results show that if the permeability coefficient of shell materials is more than 10⁻³cm/s, even for overflow with shallow depths, the infiltration rate and the extent of the saturated region will rapidly increase. Consequently, the safety factors will significantly decrease for such cases. However, if the materials with permeability coefficient less than 10⁻⁴cm/s are chosen for the shell, using this type of spillway would not endanger the stability of the downstream slope.

Keywords:

• earth overflow dam
• wedge concrete block
• seepage analysis
• slope stability
• finite element method