Foundation:
The rail way passes through different type of soil dunes, sabkha
and moving dunes. Each type needs a different method of foundation. However,
foundation is done by removing the top layer of the natural soil if it’s bad
then replacing it with good material such as sand that obtained from previous
excavation. The sand layer must be compacted properly to prevent any
settlement. Moreover, if the elevation of the foundation is higher than the
surrounding dunes the protection fence is constructed close to the foundation.
On the other hand, if the elevation of the surrounding duns is higher than the
foundation the fence must be constructed away from the foundation to prevent
the moving sand from blocking the railway or causing any troubles for the
equipment.
As you see in the drawing above the height of the foundation for
Ettihad rail way is two meters and the width is twenty meters. Moreover, the
foundation can be simply described by three basic layers the first one is the
bad layer that has to be replaced. Second is the compacted sand layer that can
be obtained by previous excavation to make the railway throughout the desert. Third,
is the (gadsh) sand and rocks mixed together to hold the sand layer because it
can be affected by the wind. Fourth, there is a thin layer of uniform uncompact
gravel. This layer is doing the same job of the cars suspension by making
and a hydraulically movement it prevent the rail equipment to wear quickly and
gives it a longer life span. Finally, the load is distributed uniformly from
the train to the steel, sleepers, and end up in the soil.
steel
ties
sleepers
To
make the rail way on the foundation we need steel, sleeper and ties. The
sleepers are casted in a factory near ALmirfa’a. However, the steel used for
the sleeper is being tensioned to get a higher compression by following the
next procedure. First, they tension the steel bars in the sleeper formwork.
Second, the concrete mix is poured into the frame and left until it dry.
Finally they steel is intentioned again so its produce a higher compressibility
force for the sleepers.in addition, the sleepers places on the foundation 0.6 –
1 meter apart depending on the place and the design for the curves. Moreover,
there two types of steel used in building the railway. Normal steel from Italy
and the head harden steel from Austria. The steel is welded to be 50 meter long
for each piece. Sleepers and the steel is taken in the work train and fixed in
their place to construct the rail way. The ties must be covered with a material
that prevents corrosion. After finishing the construction the railway must be
checked daily for blowing the sand because it can cause the train to go out
from the road. In addition for that, it can make the gravel layer more rigid
and stiff which causes the equipment to wear off faster. Major Maintenance
should be done regularly every two to one year for the steel.
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