A small bridge having total length of 6m or less than 6m
between the faces of abutments is known as culverts. Culverts
are a permanent drainage structure mainly constructed to carry roadway or
railway track over small stream or channel.
- Types of culverts
1. Arch culverts
The culverts having its superstructure
consisting of one or two arches constructed of any suitable masonry is known as
an Arch
culverts.
In these culverts segmental arches consisting
of brick masonry, stone masonry or concrete are commonly used. These arches can
be easily and cheaply constructed. The abutments and piers or these arches are constructed
sufficiently strong to take their lateral thrust arch culverts are specially suitable
where the approaches are to be constructed in cutting.
2. Slab culverts
The
culverts, having its superstructure
consisting of RCC slab which carrier the bridge floor, is known as slab
culverts.
In this type of culverts, the RCC slab of
suitable thickness is provided as simply supported over abutments and piers
which are constructed of any suitable type of masonry. Slab culverts are
suitable where the bed of the canal stream is sufficiently firm. These are
provided up to maximum span of 3m.
3. Pipe culverts
The
culverts which consists of one or more pipes placed side by side over a
concrete
Base below the embankment of a roadway or railway track is known as pipe culvert.
In
this type of culverts, one more pipes consisting of cast iron, steel or RCC are
held in positioning over a concrete base by fixing their both the ends into
masonry walls.
In pipe culverts , generally , more than one pipe , of diameter
not less than 30 cm is used. However,
their exact number and diameter depending upon the discharge and heights of the
bank. As far as possible the gradient of the pipe should not be less than 1 in
1000. Pipe culverts are suitable where the flow if water in the stream is very small.
4. Box culverts
The culverts
consisting of one or more numbers of rectangular or square opening , having their floor and top slabs constructed monolithically with abutments and pier,
is known as box culverts.
Box culverts are
usually constructed of precast rcc slabs. Small span box culverts may be constructed
of stone slab, supported masonry abutments, with brick or stone flooring. These culverts provided the least interface to traffic during construction.
Box culverts are
mainly constructed where the soil is soft and the load has to be distributed over
a wider foundation area. This type of culverts can be conventionally used for a
single span of 3 m or for double span of 6m.
