REDUCTION OF ADDITIONAL STRESS IN A BARRAGE DUE TO BLAST LOAD BY USING OPEN TRENCH

ABSTRACT
Some structures are exposed to blast load due to different reasons such as; quarry
blasting, explosions used in the construction of new roads, bomb, terrorist attack, or
other artificial explosions. Ground vibrations are part of the output of the blasting
operations. When their levels are high, they can cause damage to nearby structures.
For example; cement companies has been in operation long time ago in some areas in
Egypt using quarry blasting. Since then, new structures and new communities were
established in these areas and some nearby structures were damaged due to ground
vibrations (such as; some buildings in the 15th of May city).
The reduction of the additional stress in the structures is necessary for the safety of
the existing structures near the bl ast because even a small amount of blast can produce
a serious damage to the structures. Most design codes have specified for the seismic
vulnerability and also against vehicular collisions but there are no definite structural
design criteria for the structures exposed to typical blast loadings.
This research is intended to investigate the effect of blast load on a water structure
(barrage) when using open trench as low -cost barrier to reduce the internal forces
induced in the structure during the blast. T he barrage structure was chosen in this
research because this type of water structures is of special importance in Egypt since
they control the water management process.
The analysis of these structures should be carried out for different loading condition s.
They are normally designed for dead load, live load and other occasional loads. To
investigate the effect of blast load on the structure (with and without using trench),
Finite element analysis model under dynamic load (blast load) has been established
for the structure. Non-linear dynamic time history analysis was performed for the
structure without using trench.
Then, an open trench was used as a wave barrier to reduce the effect of the ground
vibrations induced by the blast on the internal forces of the structure. A parametric
study was carried out to investigate the effect of different factors affecting the internal
forces induced in the structural elements due to blast load such as; depth, width, and
location of the trench. These factors are import ant for the safety of structures near the
blast.