Bauhaus- Universität Weimar Faculty of Civil Engineering Laboratory of Soil Mechanics Deriving hydraulic conductivity function from soil column tests Yvonne Lins, Maria Datcheva & Tom Schanz DFG Fo 444 - TP 4 “Experimentelle und theoretische Untersuchungen teilgesättigter Reibungsmaterialien”
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Deriving hydraulic conductivity function from soil … · Deriving hydraulic conductivity function from soil column tests ... Fredlund and Xing (1994) ... Parameters θ - volumetric
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Bauhaus-Universit ät
W eimar
Fa
culty
of
Civ
il E
ngin
ee
rin
g
Labora
tory
of S
oil
Mechanic
s
Deriving hydraulic conductivity function from soil column tests
Predicted versus observed values for the different scenarios
Pre
dic
ted
valu
es
Observed values
Degree of Saturation Capillary pressure
0.0
0.2
0.4
0.6
0.8
0.0 0.2 0.4 0.6 0.8-3
-2
-1
0
1
2
3
-3 -2 -1 0 1 2 3
0.0
0.2
0.4
0.6
0.8
0.0 0.2 0.4 0.6 0.8 -3
-2
-1
0
1
2
3
-3 -2 -1 0 1 2 3
0.0
0.2
0.4
0.6
0.8
0 0.2 0.4 0.6 0.8 -3
-2
-1
0
1
2
3
-3 -2 -1 0 1 2 3
Optimized parameters.
Methods k [m2] a [1/Pa] n m α
1.Tensiometers only 2.53e-12 7.403e-4 3.016e+1 8.062e-2 2.098
2. TDRs only 1.455e-11 3.62e-4 3.019e+1 3.687e-1 4.146
3. TDRs and tensiometers 1.878e-11 4.903e-4 2.849e+3 2.783e-1 4.478
Bauhaus-Universit ät
W eimar
Fa
culty
of
Civ
il E
ngin
ee
rin
g
Labora
tory
of S
oil
Mechanic
s
Numerical analysisSWCC for 3 scenarios
SWCC: numerical and experimental results in comparison
0
10
20
30
40
50
60
0.1 1 10 100
Matric suction [kPa]
Vo
lum
etr
ic w
ate
r co
nte
nt
[%]
Results large scale tests
Initial void ratio e0=0.89
Results small scale tests
Results simulation
Bauhaus-Universit ät
W eimar
Fa
culty
of
Civ
il E
ngin
ee
rin
g
Labora
tory
of S
oil
Mechanic
s
Summary & conclusions
We study the hydraulic behavior of unsaturated granular material in the case of Hostun sand.
New experimental devices were developed, a modified pressure plate apparatus and a column type device.
SWCC & hydraulic conductivity function were established for loose specimen under variable loading path directions utilizing steady state & transient method.
SWCC & hydraulic conductivity function for Hostun sand takes place in a narrow range of suction.
Significant effect of hysteresis was found for loose specimen in the drying and wetting curves
of SWCC.
Experiments carried out under steady state & transient method show similar behavior regarding SWCC and hydraulic conductivity function.
Inverse analysis of drying cycle of sand column test results was performed in different scenarios.
Bauhaus-Universit ät
W eimar
Fa
culty
of
Civ
il E
ngin
ee
rin
g
Labora
tory
of S
oil
Mechanic
sComes-Geo: Governing Equations
1. Equation of mass balance of the dry air
2. Equation of mass balance of the liquid
3. Enthalpy balance equation for the whole media
4. Linear momentum balance equation for the whole media
5. Solid mass conservation equation
6. The balance equations 1-5 are completed by an appropriate set of constitutiveand state equations (slide 12)