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1.

a. Sheet pile coffer dom. Figure 1 shows the flow nets for seepage through a homogeneous, isotropic, permeable, fully saturated foundation rock beneath a sheet pile coffer dam. The water depths in the dam and on the downstream side of the dam are 10m and 2m, respectively. The hydraulic conductivity of the permeable foundation rock is K = 10 m/s. For simplicity, take fluid density to be p = 1000kg/m3 and the gravitational acceleration to be g = 10m/s2 in all calculations. sheet pile wall

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Fig. 1. Cross-section of the dam with a grout curtain. To scale.

Using the flow nets drawn in Fig. 1, i) Calculate the pressure at point d (the bottom of the sheet pile wall).

ii) Determine the seepage loss under the dam.

(4 marks]

(2 marks] iii) Calculate the exit velocity in units of mm/s at the three points where the flow intersect the equipotential line hl.

iv) Do you anticipate piping? Justify your answer in one or two sentences.

(6 marks]

(2 marks]

lines