Civil Engineering Reference
In-Depth Information
γ
G
e
γ
w s
b
Dry unit weight
γ
=
=
d
1
+
1
+
w
(
G e
e
+
+
)
s
Saturated unit weight
γ
=
γ
sat
w
1
(
G
−
+
1
′
=
s
Submerged unit weight
γ
γ
w
1
e
e
−
−
e
max
max
Density index
I
D
=
e
e
min
Exercises
Exercise 1.1
The results of a sieve analysis on a soil were:
Sieve size (mm)
Mass retained (g)
50
0
37.5
15.5
20
17
14
10
10
11
6.3
33
3.35
114.5
1.18
63.3
0.6
18.2
0.15
17
0.063
10.5
The total mass of the sample was 311 g. Plot the particle size distribution curve and,
from the inspection of this curve, determine the effective size and uniformity coef-
ficient. Classify the soil.
Answer
D
10
=
0.7 mm; D
60
=
5.2 mm. C
u
=
7.4. 70% gravel, 30% sand. Well graded
sandy GRAVEL - symbol GWS.
Exercise 1.2
Plot the particle size distribution curve for the following sieve analysis, given the
sieve sizes and the mass retained on each. Classify the soil.
Sample 642 g. Retained on 425
μ
m sieve - 11 g, 300
μ
m sieve - 28 g, 212
μ
m sieve
- 77 g, 150
μ
m sieve
−
173 g, 63
μ
m sieve - 321 g.
Answer
By inspection of grading curve soil is a uniform SAND - symbol SPu. This
is confirmed from the value of C
u
=
2.35.
