I guess the value of depth is unavailable! Anyway How could the value of pore pr

Question

I guess the value of depth is unavailable! Anyway How could the value of pore pressure be found?

Plot the uplift pressure distribution on the base of the dam 0.80m 1.40m 5.00m Datum Total head loss = 5m · 6 Head drop per equipotential flow line -h/Ni - 5/10 0.5 . Determine the pressure head at each point... . 0 1 23 45 10 15 20m Determine the pore pressure at each point . Net pressure on wall, unet (kPa) Point Total Elevation Pressure head z Pore pressur head h head h-z (m) Uplift pressure 10 on base of 20 30 40 (kPa) I to 5 spillway (kPa)

Explanation / Answer

Pore water pressure can be found using the given information.

Total no. of drops = 10, head loss = 5

So, i = 5/10 = 0.5

now, for point 1, no. of drops = 9, so head lost= 9*0.5 = 4.5m,

so it has a total head = 5-4.5 = 0.5m (measured from the given datum)

Elevation head at 1 = -0.8 m, so pressure/pore pressure head = 0.5 -(-0.8) = 1.3 m

Pressure= 9.81*1.3 = 12.753 kPa

Similarly for point 2, total head = 5-8*0.5 = 1m,

Pore pressure head = 1-(-0.8) = 1.8 m

Pressure = 9.81 *1.8 = 17.658 kPa

Point 3, total head = 5 - 7*0.5 = 1.5 m

Pore pressure head = 1.5 - (-1.4) = 2.9 m

Pore water pressure = 9.81 * 2.9 = 28.449 kPa

similarly for point 4 and 5, it can be found.

For the sheet pile, depth is not given, but there is a scale given below the diagram, maybe you can use that to find the depth of the points 6, 7 and 8. Once the depth from the bottom is known, pore water pressure can be found in similar way, as found for the earlier points.

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