DESIGN OF CROSSDRAINAGE STRUCTURES
Before
undertaking detailed designs of any important crossdrainage structure, collect
relevant field data is required. Basides, a note regarding the several
alternative alight surveyed and reasons for final selection of a particular
crossing site is also necessary. A lo map of the site along with the results of
subsurface explorations of the site, and stream sections at different locations
around the site should also be prepared. The following sp hydraulic data
regarding the canal and stream should be made available.
i) Canal
a)
Discharge,
depth of flow, and water level at full supply,
b)
Bed
width,
c)
Canal
bed slope and the water surface slope,
d)
Levels
of canal bed and the top of canal banks,
e)
Channel
crosssection,
f)
Characteristics
of material of the bed and sides of the channel, and
g)
Width
of roadway and type and class of IRC loading.
ii) Stream
a)
Extent
and nature of stream and its catchment,
b)
Detailed
records of rainfall in the catchment,
c)
Maximum
observed discharge,
d)
Maximum
flood level and water surface slope as observed under the highest fl condition
at the proposed site.
e)
Site
plan of the proposed crossing including contours,
f)
Log
of borehole or trial pit data.
g)
Information
about the sediment load,
h)
Characteristics of the bed material
including Manning’s
i)
Longitudinal
section of the stream for suitable distance upstream and downstre of the chosen
site for crossdrainage structure depending upon the site condition
j)
Crosssection
of the stream for about 100 to 300 m upstream and downstream the site at
intervals of 10 to 50 m,
k)
Waterways
provided in road/railway bridges or other hydraulic structures of the area,
l)
Spring
water levels at the crossing site.
Any crossdrainage
structure should preferably be located in a straight reach of tb stream
crossing the canal at right angle as far as possible. The alignment of the
canal should also be such that it results in minimum lengths of embankments
(for aqueduct and siph aqueduct structures). If required, the site of the
structure may even be shifted away from the existing stream channel, when it is
possible to divert the channel and also keep it there b construction will be
carried out in dry conditions.
Related Topics
Privacy Policy, Terms and Conditions, DMCA Policy and Compliant
Copyright © 2018-2023 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.