Civil Engineering Reference
In-Depth Information
Example 6.3:
Field vane test
A vane, used to test a deposit of soft alluvial clay, required a torque of 67.5 Nm.
The dimensions of the vane were: D
=
75 mm; H
=
150 mm.
Determine a value for the undrained shear strength of the clay.
Solution:
π
D H
2
D
H
T
=
c
1
+
u
2
3
i.e.
0 075
.
2
×
0 15
.
0 075
0 45
.
.
×
67 5
.
=
c
u
π
×
1
+
1000
kPa
2
⇒
c
=
44
kP
a
u
As mentioned above, the test procedure is described in BS 1377-9:1990 and is also to be presented in
EN ISO 22476-9 (
currently (2013) in Draft form
).
6.6.7 Testing of geotechnical structures
In addition to the tests described before, testing is often performed on geotechnical structures to assess
their performance against design requirements. The testing of geotechnical structures, such as reinforced
soil, pile foundations and ground anchorage systems, involves sophisticated and specialised processes
performed by specialist contractors. Specifications for the testing processes are covered in EN ISO 22477
(
currently (2013) in Draft form
).
6.7 Geotechnical reports
All of the information retrieved during a site investigation must be compiled in written reports and sub-
mitted to the client. The reports are the end product of all the investigation work and provide the client
and their representative consultants with the information relevant to enable an efficient foundation design
and construction plan to be evolved.
Eurocode 7 stipulates the requirements of two reports:
●
Geotechnical Design Report
(GDR), described in Eurocode 7 Part 1
●
Ground Investigation Report
(GIR), described in Eurocode 7 Part 2
The ground investigation report is the final product of the exploration programme encompassing all of
the subject areas described throughout this chapter. It comprises an account of the desk study, the series
of laboratory testing reports, the field investigation, sampling and measurement reports, the field testing
reports and any other relevant reports, together with an interpretation of the ground conditions across
the site. The report will also include any limitations and constraints of the various test results so that the
designer can assess the relevance of the test results to the geotechnical design. The report can also include
any derived values of geotechnical properties (see Section
5.4.1)
.
The geotechnical design report contains the GIR along with the results from the calculations performed
to verify the safety and serviceability during the geotechnical design (see Chapter
5)
. Along with the
