The cross-section of a square unlined tunnel is shown below. The central axis of the tunnel is located 20ft below the ground surface, and impermeable bedrock is located 20ft below the central tunnel axis. The profile is completely saturated. Assume that the soil is homogeneous and has an isotropic hydraulic conductivity of 1x10-8ft/s. Z 10ft 2. 20ft CL. 3 8ft 4. 20ft 5 10ft Impermeable rock a) draw a flow net by hand for the profile. Draw at least 5 flow lines and 5 equipotential lines. (In this case, a computer-generated figure is not mandatory, and a hand drawn figure is acceptable) b) in a spreadsheet program or with code, construct a computer-generated flow net for the profile. Show at least 5 flow lines and 5 equipotential lines in your figure. The equipotential lines must be determined by the computer program, while the flow lines can be superimposed on top using a drawing tool. (Remember that flow lines and equipotential lines always intersect at 90 angles.)