(Solved): A dam, shown in Figure 1, retains \( 10 \mathrm{~m} \) of water. A sheet pile wall (cutoff curtain) ...

A dam, shown in Figure 1, retains \( 10 \mathrm{~m} \) of water. A sheet pile wall (cutoff curtain) on the upstream side, which is used to reduce seepage under the dam, penetrates \( 7 \mathrm{~m} \) into a \( 20.3 \mathrm{~m} \) thick silty sand stratum. Below the silty sand is a thick deposit of practically impervious clay. The average hydraulic conductivity of the silty sand is \( 2.0 \times 10^{-4} \mathrm{~cm} / \mathrm{s} \). Assume that the silty sand is homogeneous and isotropic. (a) Draw the flownet under the dam. (b) Calculate the flow rate. (c) Calculate and draw the porewater pressure distribution at the base of the dam. (d) Determine the uplift force. (e) Determine the maximum hydraulic gradient. (f) Will piping occur if the void ratio of the silty sand is \( 0.8 \) ? (g) What is the effect of reducing the depth of penetration of the sheet pile wall?