Question

4. An earth dam in Figure 3 composes of a uniform material. It has a horizontal drainage blanket at the base that extends from the downstream toe to a distance of 30 m. The embankment has a permeability of 2.0 x 10-6 m/s. The freeboard is 3.0 m. Draw the phreatic line and thus determine the seepage through the dam. 5. The specific weight of the dam shown in Figure 3 is 2.63, and the coefficient of friction between dam and the foundation is 0.53. The depth of the water is 27.5m when the reservoir is filled to design capacity. Assume that the uplift force has a triangular distribution with the maximum magnitude of 60% of the full hydrostatic pressure at the heel of the dam. Determine the force ratios against sliding and overturning. Neglect earthquake and sedimentation forces. 8 m 1.0 1.0 30 m 1.0 2.0 30 m Figure 3