Geoscience Reference
In-Depth Information
Figure 5.14
Relationship between natural water content
w
n
and void ratio
e
o
(
after
Oikawa and Igarashi,
1997).
H
p
is the accumulated compression of the specimen to time
t
p
; normally when
H
p
extends a horizontal line this will give
d
100
, where 100% consolidation occurs.
Oikawa and Igarashi (1997) propose the following equations (5.5 and 5.6) for
calculating
c
v
. The only input needed for these is the natural water content, without
having to do the consolidation test.
⎡
⎣
⎤
⎦
0
.
85
1
exp (1
.
85
p
)
0
.
45
1
−
1
exp
2
.
91
p
=
−
e
f
2
.
47
1
w
(5.5)
0
.
39
n
1
.
51
W
n
+
0
.
20
e
o
+
e
f
1
.
12
(
W
n
−
log
(1
+
e
o
)
log
c
v
=
−
0
.
21)
0
.
68
+
2
e
o
−
e
f
+
log (
p
−
p
o
)
−
1
.
06
(5.6)
where
e
f
and
e
o
are the final and initial void ratios,
w
n
is the water content, and
p
is the consolidation pressure in kg cm
−
2
.
c
v
is in cm s
−
1
. Figure 5.14 shows the plot of
water content and void ratio from Oikawa and Igarashi.
Kazemian andHuat (2009a) have studied the compressibility parameters of fibrous
peat. High levels of organic matter are an indicator of high compressibility and swell
characteristics of the soils (Mesri and Ajlouni, 2007; Puppala
et al.
, 2007; Kazemian
et al
., 2009). Fibrous peat undergoes large settlements in comparison to clays when
subjected to loading. The compression behaviour of fibrous peat varies from the com-
pression behaviour of other types of soil in two ways. First, the compression of peat is
