Hydro-Mechanical Properties of an Unsaturated Frictional Material

7.4. UNSATURATED HYDRAULIC CONDUCTIVITY 155
Unsat. hydr. conductivity (10 -4m/s)
Unsat. hydr. conductivity (10-4m/s)
Unsat. hydr. conductivity (10 -4m/s)
3.0
2.5
2.0
1.5
1.0
Unsat. hydr. conductivity (10-4m/s)
3.0
2.5
2.0
1.5
Initial drainage
1st and 2nd drainage
1.0
1st and 2nd imbibition
Childs and Collis George (1950)
Initial void ratio e0=0.63
Initial drainage
1st and 2nd
drainage
0.5
TDR/T 160 mm
TDR/T 260 mm
0.5
0.0
TDR/T 360 mm
0.0
0.1
3.0
1
Matric suction (kPa)
10 0.1
3.0
1
Matric suction (kPa)
10
Mualem (1976)
Mualem (1976)
2.5
2.0
1.5
1.0
0.5
0.0
3.0
2.5
2.0
1.5
1.0
0.5
Childs and Collis
George (1950)
Initial void ratio e = 0.89
Flow rate » 30 ml/min
Flow rate » 100 ml/min
1st and 2nd imbibition
TDR/T 70 mm
1st and 2nd imbibition
Unsat. hydr. conductivity (10-4m/s)
0.1 1 10
1st and 2nd imbibition
Initial drainage
1st and 2nd drainage
Matric suction [kPa]
Fredlund et al. (1994)
Unsat. hydr. conductivity (10-4m/s)
2.5
2.0
1.5
1.0
0.5
0.0
3.0
2.5
2.0
1.5
1.0
0.5
1st and 2nd imbibition
0.1 1 10
1st and 2nd imbibition
Matric suction [kPa]
Initial drainage
1st and 2nd
drainage
0.0
0.0
0.1 1 10 0.1 1 10
Matric suction (kPa)
Initial drainage
1st and 2nd
drainage
Matric suction (kPa)
Fredlund et al. (1994)
Initial drainage
1st and 2nd
drainage
Figure 7.13: Unsaturated hydraulic conductivity from sand column test I (transient state
test) determined by using statistical models (loose and dense specimen)
hydraulic conductivity is not changing in the saturated zone. When reaching the air-entry
value the unsaturated hydraulic conductivity decreases drastically. In the residual zone, the
unsaturated hydraulic conductivity approaches a zero value. No significant changes in the un-
saturated hydraulic conductivity were observed in the residual zone along the drainage as well