Question: the dam shown below from holtz and kovacs 1981 is...
The dam shown below (from Holtz and Kovacs 1981) is founded on an alluvial deposit overlying tight impervious bedrock. The hydraulic conductivity of the alluvial deposit is 0.0002 cm/s.
(a) Draw a flow net for the dam as shown in the first figure below. Compute the seepage rate beneath the dam, and the pore water pressure at point A.
(b) Draw a flow net for the dam as shown in the second figure below. For this case, a sheet-pile cutoff wall extends deep into the alluvium, but does not reach the bedrock. Compute the seepage rate beneath the dam and the pore water pressure at point A.
(c) The sheet-pile wall for part (b) extended about 81% of the way to the bedrock (i.e., 14 m/17.2 m). Was the seepage rate beneath the dam reduced by a similar percentage, a greater percentage, or a lesser percentage? What was the percent reduction in the pore pressure at point A?