Flow analogy and flow net
Figure E3.6 shows the cross-section of an impervious dam above the pervious aquifer. A reservoir is located both upstream and downstream of the dam wall. The difference in reservoir elevation is 32 m and the dam length is 360 m. The aquifer consists of silty sand with a hydraulic conductivity of 1.7×10-6 m/s.
(a) On graph paper, sketch the flow net beneath the dam wall. Use at least 5 stream tubes. On graph paper, the sketch must be an undistorted copy of the sketch below (Fig. E3.6).
(b) Calculate the seepage flow rate beneath the dam.
(c) Calculate the uplift force acting on the dam foundation.
(d) Calculate the sliding force exerted by the aquifer water pressure on the dam foundation.
(e) Discuss and justify design techniques to reduce the seepage and the uplift pressure force.
