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was similar to the previous detonation event as the blasts were of similar intensity
and at the same distance from the wall. As a result, the diffracted wave, which
caused the pressure to increase on the back of the front panels, pushed the front
panels further out. When the concrete panels were pushed further outward,
reinforcement strips at the upper layers suffered pullout failure as the dynamic
force acting on the back of the concrete panels was greater than the pullout
resistance of the reinforcement strips attached to the respective concrete panels.
The pullout resistance of the reinforcement strips for the lower layers was higher
due to larger overburden pressure. This pullout resistance was higher than the
punching shear strength of the concrete.
Therefore, the dynamic forces acting on the back of the front panels were
less than the pullout resistance of the reinforcement strips at the lower layers;
these reinforcement strips did not suffer pullout failure. However, the tension
developed in the reinforcement strips at the time when the dynamic force was
acting was greater than the punching shear strength of the concrete. As a result,
the connections between reinforcement strips and the concrete panels were
sheared away from the concrete panels by the large tension force in the
reinforcement strips. Some of the concrete panels were broken apart because
weakened crack lines had already developed in the concrete panels during
detonation event MD11-E2.
In summary, the RS wall performed better as a blast-resistant structure
when 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. The different behavior of these two wall systems is
based on the observations of the field trial results.
The comparisons of different behavior of the two different wall
systems were based on detonation events MD5-E2 and MD5-E3 for the RS
wall, MD11-E2 and MD11-E3 for the RE wall of similar dimensions. The charge
type (bare or cased), charge weight (100 kg), and distance (5m) of the detonation
point from the walls for these detonation events were the same. The acceleration
and incident blast pressure on the front of the walls were as high as 5000 g and
200 kPa, respectively, as suggested by the measurements made in the RS wall.
After detonation event MD5-E2, some areas of geotextile facing melted
and some areas of the geotextile facing were cut by the blast fragments, and the
fragments were eventually stopped in the soil mass. There was similar
observation at the RE wall after detonation event MD11-E2 as the blast fragments
cut through the concrete panel facings, drilled a hole of conical shape into the
soil, and eventually stopped at the base of the holes. This showed that both wall
systems were effective in absorbing the blast fragments. However, the RE wall
has a distinct disadvantage having hard and brittle reinforced concrete panel
facings. When the blast fragments cut through the concrete panels, it caused the
concrete to fracture and concrete debris to fly out at high speed, which can be
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