Geosynthetics April/May 2023 - 20

Motorway underpass using geomembranes as a groundwater barrier
raft, the submerging process could start
(Figures 1, 9 and 10).
This submerging process was accomplished
as follows: After completing the
excavation, Genap installed a drainage
system onto the bottom of the excavation
(Figure 8). This system was used to
pump the water underneath the geomembrane
onto the top of the geomembrane.
During this process the geomembrane
FIGURE 8 Drainage system installation
sank to the bottom under its weight during
pumping because the material is
heavier than water. Once the geomembrane
reaches the bottom, the pumps
stopped because there is no more water
underneath the geomembrane. The submerging
process was complete.
Divers checked once again that the
geomembrane was fully pressed onto
the bottom.
Subsequently, geoelectrical leak detecFIGURE
9 Aerial view of the geomembrane being pulled over the water surface
tion was carried out and it was demonstrated
that the geomembrane construction
was 100% watertight. The geoelectric
measurement system used for this was
the so-called electrical flux tracking. For
this process, an electric field is applied
outside the structure, which is conducted
to the other side of the structure using an
opposing pole. The power flow follows
the easiest route and moves through any
openings in the geomembrane construction.
The electrical potential is measured
using sensors placed in a grid. Elevated
potentials indicate leaks.
The last step was to install the third
layer, the protection geotextile on top of
the geomembrane. When this layer was
submerged to the bottom, a drainage system
was installed on top of the protection
geotextile that would be needed to dewater
the pit after filling it with ballast sand.
Hydraulic excavators placed the balFIGURE
10 Close-up of geomembrane being pulled over the water surface
20
Geosynthetics | April May 2023
last sand back into the excavation in a
controlled manner. After sufficient sand
had been replaced, the construction was
pumped dry using the drainage system
(Figure 11).

Geosynthetics April/May 2023

Table of Contents for the Digital Edition of Geosynthetics April/May 2023

Geosynthetics April/May 2023 - Cover1
Geosynthetics April/May 2023 - Cover2
Geosynthetics April/May 2023 - 1
Geosynthetics April/May 2023 - 2
Geosynthetics April/May 2023 - 3
Geosynthetics April/May 2023 - 4
Geosynthetics April/May 2023 - 5
Geosynthetics April/May 2023 - 6
Geosynthetics April/May 2023 - 7
Geosynthetics April/May 2023 - 8
Geosynthetics April/May 2023 - 9
Geosynthetics April/May 2023 - 10
Geosynthetics April/May 2023 - 11
Geosynthetics April/May 2023 - 12
Geosynthetics April/May 2023 - 13
Geosynthetics April/May 2023 - 14
Geosynthetics April/May 2023 - 15
Geosynthetics April/May 2023 - 16
Geosynthetics April/May 2023 - 17
Geosynthetics April/May 2023 - 18
Geosynthetics April/May 2023 - 19
Geosynthetics April/May 2023 - 20
Geosynthetics April/May 2023 - 21
Geosynthetics April/May 2023 - 22
Geosynthetics April/May 2023 - 23
Geosynthetics April/May 2023 - 24
Geosynthetics April/May 2023 - 25
Geosynthetics April/May 2023 - 26
Geosynthetics April/May 2023 - 27
Geosynthetics April/May 2023 - 28
Geosynthetics April/May 2023 - 29
Geosynthetics April/May 2023 - 30
Geosynthetics April/May 2023 - 31
Geosynthetics April/May 2023 - 32
Geosynthetics April/May 2023 - 33
Geosynthetics April/May 2023 - 34
Geosynthetics April/May 2023 - 35
Geosynthetics April/May 2023 - 36
Geosynthetics April/May 2023 - 37
Geosynthetics April/May 2023 - 38
Geosynthetics April/May 2023 - 39
Geosynthetics April/May 2023 - 40
Geosynthetics April/May 2023 - 41
Geosynthetics April/May 2023 - 42
Geosynthetics April/May 2023 - 43
Geosynthetics April/May 2023 - 44
Geosynthetics April/May 2023 - Cover3
Geosynthetics April/May 2023 - Cover4
https://www.nxtbook.com/ata/geosynthetics/geosynthetics-october-november-2024
https://www.nxtbook.com/ata/geosynthetics/geosynthetics-july-august-2024
https://www.nxtbook.com/ata/geosynthetics/geosynthetics-case-studies-guide-2024
https://www.nxtbook.com/ata/geosynthetics/geosynthetics-april-may-2024
https://www.nxtbook.com/ata/geosynthetics/geosynthetics-february-march-2024
https://www.nxtbook.com/ata/geosynthetics/geosynthetics-december-2023-january-2024
https://www.nxtbook.com/ata/geosynthetics/geosynthetics-october-november-2023
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https://www.nxtbook.com/ata/geosynthetics/geosynthetics-april-may-2023
https://www.nxtbook.com/ata/geosynthetics/geosynthetics-february-march-2023
https://www.nxtbook.com/ata/geosynthetics/geosynthetics-december-2022-january-2023
https://www.nxtbook.com/ata/geosynthetics/geosynthetics-october-november-2022
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https://www.nxtbook.com/ifai/geosynthetics/geosynthetics-december-2021-january-2022
https://www.nxtbook.com/ifai/geosynthetics/geosynthetics-october-november-2021
https://www.nxtbook.com/ifai/geosynthetics/geosynthetics-august-september-2021
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