Measurement of Properties - Geotechnical Engineering Investigation - page 154

EXAMPLE
Given : wef = 123.6 lbs./ ft.

3

G s = 2.625 = 20.0%

wet
1 +

123.6
1 + 0.20

103.0 lbs./ft. 3 = =

1 Find: d =

Find: e =

wet

ω

( G s ) (62.4)
d
d
62.4 (G s )

(2.65) (62.4)
103.0

2 − 1 = − 1 = 0.605

d

e n
sgt

103.0
62.4 (265)

80

2

n = 1

− 45

= 1 − = .377 or 37.7%

1.3

sat = 0.605
2.65 .228 or 22.8%
Degree of saturation: S =

e
G s =

2

=

sat

.200
.228

= = .877 or 87.7%

G s

1

40

1.0

2

1.4

1.3

90

%

55%

35

1.1

1.2

1.5

70

1.1

1.2

30

1.6 100 50

1.0

40

38

80

1.3

36

0.9

1.7

34

25

45

32

1.4

0.8

110

30

90

1.8

28

2.55

0.7 1.5

26

40

20

24

1.9

1.6

100

0.6

120

22

2.60

35

1.7

20

2.0

0.5

110

15

18

1.8

130

30

2.1 16

2.65

0.4

1.9

120

14

2.2

2.0

25

10

12

140

0.3

130

2.70

2.1

2.3

10

20

2.2

2.4 150

5

2.75

FIGURE 3.2
Nomograph to determine basic soil properties. (From USBR, Earth Manual, U. S. Burean of Reclamation,
Denver, CO, 1974. With permission.)

Significance
D R is used for classification of the degree of in situ compactness as given in Figure 3.8
or, more commonly, to classify in situ density as follows: very loose (0-15%), loose
(15-35%), medium dense (35-65%), dense (65-85%), and very dense (85-100%) (see
Table 3.23 for correlations with N values of the Standard Penetration Test (SPT)). Void
ratio and unit weight are directly related to D R and gradation characteristics.
Permeability, strength, and compressibility are also related directly to D R and gradation
characteristics.