Floors

soil

permeability index

(%)

Internal angle of friction φs (degrees)

Soil cohesion

c (kPa)

Crushed rock

47 ± 7

0

Clean gravel

0

40 ± 5

0

Silty gravel

2 - 6

36 ± 4

≈ 0

Clay gravel

7 - 12

34 ± 4

≈ 0

Clean sand with large grain size

0

40 ± 4

0

Clean sand with uniform grain size

0

36 ± 6

0

Slightly to moderately silty sand

2 - 6

34 ± 3

≈ 0

Slightly to moderately clayey sand

6 - 12

32 ± 3

≈ 0

Clayey sand

9 - 15

27 ± 3

5 ± 5

Silt

2 - 6

33 ± 4

≈ 0

Clayey silt

4 - 10

30 ± 4

15 ± 10

Silty clay

12 - 18

27 ± 4

20 ± 10

Clays

−20

20 ± 4

20 ± 10

−40

15 ± 4

25 ± 10

−60

11 ± 4

2

>100

<8

2