Geoscience Reference
In-Depth Information
7.13 Preconsolidation stress from shear wave velocity
The shear wave velocity for low preconsolidation pressures would require near
surface (Rayleigh) waves to be used.
Table 7.13 Preconsolidation pressure from shear wave velocity (from Mayne et al., 2002).
Shear wave velocity
V s
m/s
20
40
70
100
150
250
500
Preconsolidation pressure
P c
kPa
9
24
55
92
168
355
984
For intact clays only
For fissured clays P c =
2000 to 4000 with V s
=
150 to 400m/s
7.14 Over consolidation ratio from Dilatometer
Many correlation exists for OCR to dilatometer measurement of K D
K D
=
1.5 for a naturally deposited sand (Normally Consolidated)
K D
=
2 for a Normally Consolidated clays
(0.5 K D ) . 56 (Kulhawy and Mayne, 1990)
OCR
=
Table is for insensitive clays only
Table 7.14 Over consolidation from dilatometer testing using the above relationship.
K D
1.5-3.0
2.5-6
3-8
5-10
8-20
12-35
20-50
=
OCR
1
2
3
5
10
20
30
For intact clays only
For fissured clays OCR
=
25 to 80 with K D
=
7to20.
7.15 Lateral soil pressure from Dilatometer test
The Dilatometer is useful to determine the stress history and degree of over
consolidation of a soil.
Table 7.15 Lateral soil pressure from Dilatometer test (Kulhawy and Mayne, 1990).
Type of clay
Empirical
Over consolidation ratio (OCR)
parameter
β
o
Formulae
2
5
10
15
Insensitive clays
0.5
(K D
0.5) 1.56
1.0
4.2
12
23
0.35) 1.56
Sensitive clays
0.35
(K D
N/A
2.4
7
13
0.27) 1.56
Glacial till
0.27
(K D
N/A
1.6
4.7
9
0.75) 1.56
Fissured clays
0.75
(K D
1.9
7.9
23
44
 
 
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