Civil Engineering Reference
In-Depth Information
Soil investigation
The field research was carried out in a number of phases at the position of
the boring trajectory. Field research had already been undertaken at the
time of the planning of a cross-river connection, being a combination of a
bridge-dam-immersed tunnel (in the late 1980s early 1990s). The results of
which however, did not provide a picture of the bedding at the greater
depths, which were relevant for the bored tunnel.That is why four additional
deep drillings were undertaken in combination with seismic research. This
research had an orientating character and was particularly meant to provide
an insight into the properties of the layers that lay deeper and to determine
the layer separations. On the basis of this data, the contractor set up and
carried out an extensive and detailed soil investigation - contractually the
construction and boring risks were his responsibility. In his opinion, this
made sufficient geotechnical information available for the definite design
and the implementation of the bored tunnel as well as the access ramps.
Fig. 7.5
Drillings and cone
penetration tests;
nature and size of the
field research
Type
Trajectory section
Number
Period undertaken
Zeeuwsch-Vlaanderen bank
4
October through November 1994
Westerschelde
33
July through September 1994
September 1994
March 1995
4
2*
Zuid-Beveland bank
3
September 1994
*
Additional drillings carried out by the Directorate-General for Public Works and
Water Management Zeeland Department
Zeeuwsch-Vlaanderen bank
29
October 1994
Westerschelde
30
4
August through October 1994
Zuid-Beveland bank
September 1994
PM
DM
MP
Zeeuwsch-Vlaanderen bank
1
1
0
1
October 1994
Westerschelde
2
0
August through October 1994
Zuid-Beveland bank
0
1
1
September 1994
PM pressiometer
DM
dilatometer
MP in-situ pore permeability probe
Field research - drillings and cone penetration tests
A large portion of the field research consisted of (46) drillings and (63) cone
penetration tests. Due to the rigidity of the Boom clay the drillings could be
carried out as core drillings.The depth of the drillings and cone penetration tests
varied from approximately 30 metres
NAP
in the Pas vanTerneuzen and Everingen.The Boom clay and the sand deposits
under the Boom clay were continually sampled and local sampling also
took place of sand deposits above the Boom clay. The sample yields of the
core drillings were negatively influenced locally by the relatively high sand
content of the Boom clay. In total however, the sample yield appeared to be
more than adequate for the drilling descriptions and the carrying out of lab-
oratory tests.
All cone penetration tests were carried out as so-called coil cone penetra-
tion tests which made it possible to penetrate the entire thickness of the
Boom clay stratum. Due to the great depth of water in the Pas vanTerneuzen
(approximately 40 metres) the activities had to take place from a floating
NAP on the banks to 65 metres
Search WWH ::
Custom Search