2970
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
working platform over soft soil in Vung Tau in Vietnam using
one metre thick of geocell mattress to support a two metre thick
MSL as a loading platform for the heavy crawler crane exerting
a contact pressure of 500 kPa (Ong et al., 2011). The two
loading platform performances are compared and it is found that
both loading platforms performed satisfactorily with settlement
of less than 50 mm. In 2011, geocell mattress and MSL were
used in another project on soft ground for a container yard in
Gebeng, Kuantan in Malaysia. In this case one metre thick of
geocell mattress were used to support the container pavement of
760 mm thick aggregate base course stabilised with two layers
of TriAx geogrid (MSL) and interlocking paving block finishes.
Figure 1. General condition of working platform without gegorids.
(after Yong, Chan et al., 1990)
2 PASIR GUDANG FABRICATION YARD
The rehabilitation of the muddy platform started by removing
the top 700 mm of residual soil fill (Figure 2). One layer of the
biaxial geogrid was then placed on top of the compacted clay
fill at excavated level. Backfilling using compacted quarry
waste, a granular material, carried out after suitable subsoil
drains were laid (Figure 3). Another layer of biaxial geogrid
was placed before filling with compacted quarry waste for a
further 300 mm.
Figure 2. Schematic section of rehabilitated working platform.
(after Chan, 2000)
The completed platform formation was tested and at 30
passes of the 2.3 MN crawler crane carrying 700 kN load and
the resulting deformation measured was 37 mm (Chan, 2000),
with decreasing rate of deformation after each pass, which was
acceptable by the fabricator. Settlements on the subgrade and
outside the crane track were measured (Figures 4 & 5). The
rehabilitated fabrication yard was in use after handing over to
the fabricator (Figure 6).
Figure 3. Platform rehabilitation work in progress. (after Yong, Chan
et al., 1990)
2 layers of
geogrid
Measuring
points
230t crane
carrying 70t
load
Soft clay subgrade
Figure 4. Settlement measuring points.
-400
-300
-200
-100
0
100
0
5 10 15 20 25 30 35 40
Settlement (mm)
Number of passes
Edge of track Under track On subgrade
Single
track
Multiple
track
Single
track
Figure 5. Plot of settlement versus number of passes.
3 WORKING PLATFORM IN VUNG TAU
In Vietnam, the geocell mattress with MSL was adopted for the
construction of the working platform for an offshore facilities
fabrication yard in Vung Tau, Vietnam (Ong et al., 2011). The
working platform was required to take loading from heavy
crawler crane tracks up to 50 t/m². The exhibited design uses
conventional reinforced concrete pile-raft foundation system to
support the working platform. However, in order to accelerate
the construction works, alternative solutions using geocell
mattress with MSL was selected not only will it reduce the
construction time but also being more economic and
sustainable. This geocell mattress with MSL was designed to
form a working platform to support the movement of crawler
cranes with 2 m wide and 13.7 m long crane tracks separated by
a clear distance of 7.6 m. The maximum load to be supported on
