Geoscience Reference
In-Depth Information
1.13 Sample size
•
The sample size should reflect the intent of the test and the sample structure.
•
Because the soil structure can be unknown (local experience guides these deci-
sions), then prudent to phase the investigations as suggested in Table 1.1.
Table 1.13
Specimen size (Rowe, 1972).
Clay type
Macro-fabric
Mass, permeability, km/s
Parameter
Specimen size (mm)
Non fissured
None
10
−
10
C
u
,C
37
sensitivity
5
m
v
,c
v
76
<
High pedal, silt,
10
−
9
to 10
−
6
C
u
,
100-250
sand layers,
C
37
inclusions,
m
v
75
organic veins.
c
v
250
Sand layers
2mm
10
−
6
to
10
−
5
C
37
>
at
0.2 m spacing.
m
v,
c
v
75
<
Sensitivity
5
Cemented with
C
u
,
50-250
>
any above.
C
,
m
v,
c
v
Fissured
Plain fissures
10
−
10
C
u
,
250
C
,
100
m
v,
c
v
75
Silt or sand fissures
10
−
9
to 10
−
6
C
u
,
250
C
,
100
m
v,
c
v
75
Jointed
Open joints
100
Pre-existing slip
C
r
,
150 or remoulded
r
1.14 Quality of site investigation
•
The quality of an investigation is primarily dependent on the experience and
ability of the drilling personnel, supervising geotechnical engineer, and ade-
quacy of the plant being used. This is not necessarily evident in a cost only
consideration.
•
The Table below therefore represents only the secondary factors upon which to
judge the quality of an investigation.
•
A good investigation would have at least 40% of the influencing factors
shown, ie does not necessarily contain all the factors as this is project and site
dependent.
•
An equal ranking has been provided although some factors are of greater
importance than others in the Table. This is however project specific.
•
The table can be expanded to include other factors such a local experience, prior
knowledge of project/site, experience with such projects, etc.
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