Theory of Water Flow through Unsaturated Soils - Unsaturated Soil Mechanics in Engineering Practice - page 343

10 − 12

10 − 13

10 − 14

10 − 15

Lai et al., (1976)
Millington and Quirk (1961)
Millington (1959)
Marshal (1959)
Penman (1940)
Abu-El-Sha'r & Abriola (1997)

10 − 16

10 − 17

10 − 18

10 − 19

10 6

0.1 1 10 100 1000 10,000 100,000

Soil suction, kPa

Figure 7.17 Coefficient of vapor permeability with respect to soil suction when assuming var-
ious tortuosity functions (after Ebrahimi-Birang et al., 2004).

Table 7.3 Tortuosity Coefficients from the Literature

Table 7.4 Maximum Values of Vapor Coefficients
of Permeability

Reference αβ

Soil Texture ( k v ) max ,m/s

β 5 / 3

Lai et al. (1976)

β 10 / 3 n 2 10 − 14

Millington and Quirk (1961) Silty sand 2 . 42 ×

β 3

10 − 14 Silt 1 . 76 ×

Millington (1959)

10 − 14 Sand 1 . 63 ×

β 2 Marshal (1959)

Penman (1940) 0.66 N

Abu-El-Sha'r and Abriola (1997) 0.435 N

Note : αβ = computed using Eq. 7.22, n = porosity.

10 − 13

10 − 14

10 − 15

10 − 16

Sand
Silt sand
Silt
Residual conditions

10 − 17

10 6 0.1 1 10 100 1000 10,000 100,000

Soil suction, kPa

Figure 7.18 Vapor permeability measurements for three soils (after Ebrahimi-Birang et al.,
2004).