Braja M Das, Principal of Geotechnical
Engineering , fourth edition, PWS Publishing Company, 1998, Boston
Muni Budu, Soil Mechanics and Foundations , 2nd edition, John Wiley & Sons, 2007, USA
R.F. Craig, Soil Mechanics , (English & terjemahan Prof.Dr.Ir Budi S Supandji)
Cernica, J.N., Soil Mechanics , John Wiley & Sons, 1995
Holtz, R.D., Kovacs, W.D., An introduction to
Geotechnical Engineering , Prentice Hall, N.J.,
1981
Bernoulli’s law
Darcy’s law
Flow
Determining hydraulic conductivity
Common knowledge:
Water flow from higher place to the lower
places
g z v h u
w
2
2
g z v h u
w
2
2
Pressure
Head Velocity
Head
Elevation Total Head
Head
In soil, the velocity of the flow is very small, it can be neglected
u z h
w
L i h
B
A h
h
h
P = 0 (= P
atm)
Pressure Head (increases with depth below surface)
Elevation
Head
Elevation Head ith height above datum)
Elevation
P = 0 (= P
atm)
Total Head (constant: hydrostatic equilibrium)
Elevation
Head Elevation datum
Total head = Pressure
head + Elevation head
Hydorstatic Pressure
Classifications : one, two or three dimensional
◦ One dimensional flow :
flow with fluid parameter such as pressure, velocity, constant temperature toward intersection
perpendicular to flow direction
◦ Two dimensional flow :
cofferdam cells (sheet pile wall), concrete dam; earth dam and levees
◦ Three dimensional flow:
i k
v
v = discharge velocity
k = hydraulic conductivity i = hydraulic gradient
A v
q
q = flow rate
A = cross sectional area
V V V
v L
A
L A A
v A
A A
v v
A v A
A v q
A A
A
A v vA q
v s v
v s v
v s v
s
v s s
v s v
v s
The hydraulic conductivity of soils depends on several factors: fluid viscosity, pore size distribution, grain-size distribution, void ratio, roughness of mineral particles, and degree of soil saturation.
In clayey soils, structure plays an important
role in hydraulic conductivity.
Constant Head Test
Falling Head Test
The constant head test method is used for permeable soils (k>10-4 cm/s), and the falling head test is mainly used for less permeable soils (k<10-4 cm/s).
Permeability of granular soils (U.S.
Dept of Navy, 1971)
Variation of void ratio with hydraulic
conductivity of clayey soil (Tavenas et al, 1983)
eq
H H H H n
H
k H k H k H k H
k H
n
1 ...
3 2
1 2 3
1
Vn
n V
V V
eq V
k H k
H k
H k
H k H
...
3 2
1
3 2
1
