Geoscience Reference
In-Depth Information
reasonable values obtained from pullout tests for the PEC200 geotextile used
with Singapore tropical residual soil.
7 CONCLUSION
From the field and photographic comparison, it is observed that the RS wall was
more suitable to be used as a blast-resistant structure as compared to the RE wall.
This was due to the different behavior of the facing and reinforcement materials
used for the reinforced soil structures when subjected to blast loading and also the
different mechanisms of interaction between the blast wave and the RS and RE
walls.
After the blast, some areas of geotextile facing melted and some areas were
cut by the blast fragments, which eventually stopped in the soil mass. There was
similar observation for the RE wall after blast as the blast fragments cut through
the concrete panel facings, drilled a hole of conical shape into the soil, and blast
fragments are embedded at the end of the holes. This showed that both wall
systems were effective in absorbing the blast fragments. However, there is a
disadvantage of the RE wall with rigid reinforced concrete panel facings, which
can produce high-speed flying concrete debris dangerous to human occupants. On
the other hand, no hard flying debris was produced when the geotextile facing
was cut by the blast fragments.
During the blast, no strain gauge in the RS wall registered any significant
changes, with additional peak strain of less than 0.2%. In addition, there was only
small horizontal inward depression of the RS wall, estimated to be about 50 mm
at maximum. This implies that the geotextile reinforcement was not subjected to
additional dynamic strain during and after the blast. However, there was
extensive outward deformation of the RE wall front and side panels after the
blast. Hence it can be deduced that large additional tension developed in the
reinforcement strips during and after detonation. This comparison implies that
the stability of the RE wall was greatly affected by the blast loading whereas the
stability of the RS wall was not much affected. This difference in the behavior of
the two wall systems was mainly due to the different facing materials. Geotextile
facing was porous enough for the blast wave to pass through whereas concrete
panel facing was like a rigid wall where the wave diffraction process would occur
when the blast wave enveloped the wall and passed around it, inducing a net
outward pressure on the back of the wall. The diffracted wave caused the pressure
on the back of the wall to increase and pushed the wall outward.
At the end of several detonation events, more exposed areas of geotextile
facing of the RS wall were melted and cut by fragments, but there was still no
significant deflection or bulging of the RS wall facing. However, the front panels
of the RE wall collapsed and the soil mass behind the wall spalled out.
Search WWH ::
Custom Search