CEE4405 Homework 5 Solution Key - Georgia Institute Of Technology CEE 4405

Georgia Institute of Technology School of Civil and Environmental Engineering
CEE4405 Homework #5 Solution Key Assigned Wednesday 10/04/17
Geotechnical Engineering Page 1 of 4 Due Monday 10/16/17 at 4:00 pm

1) A one-dimensional hydraulic conductivity test is shown in the figure below.
a) Determine the total head, elevation head, and pressure head at the inlet and outlet of the
soil sample.
b) If the soil has the following properties: porosity n = 0.42, hydraulic conductivity k = 0.025
cm/sec, and sample length l = 20 cm, determine the approach velocity and the seepage
velocity for the hydraulic conductivity test.




Solution

Head @ Point Total, H (cm) Pressure, h (cm) Elevation, Z (cm)
A 35 0 35
B 35 15 20
C 5 5 0
D 5 0 5
Point B and C presents the inlet and outlet of the soil sample, respectively.

Approach velocity:
Δ𝐻 𝑐𝑚 35 − 5 𝑐𝑚
𝑉𝐴 = 𝑘 ∙ 𝑖 = 𝑘 ∙ = 0.025 ∙ = 𝟎. 𝟎𝟑𝟕𝟓 𝒄𝒎/𝒔
𝐿 𝑠 20 𝑐𝑚
Seepage velocity:
𝑐𝑚
𝑉𝐴 0.0375 𝑠
𝑉𝑛 = = = 𝟎. 𝟎𝟖𝟗𝟑 𝒄𝒎/𝒔
𝑛 0.42




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