The forces acting on a cross section of
pipeline arise from three main sources:
A) Weight of overlying fill, including any local
surcharge.
B) Soil pressures transmitted to
the pipe from surface loads, i.e. traffic and other
transient loads.
C) Supporting reaction below the pipe.
The established method for calculation of loads on
buried rigid pipes is summarised in BS EN 1295 National
Annex A, the principles of which are explained in the
Technical
Design Guide – Section 1.2 Structural
Design.
In general, pipelines are laid in trenches and the
pipes are designed to carry the backfill, traffic loads
and when the diameter is 600mm or more, part of the
water load within the pipe.
To improve the load carrying capacity of the pipe,
it may be installed using an appropriate bedding class
chosen from a number of alternatives. Each type of
bedding is allocated a “bedding factor” (Fm)
which may be regarded as a multiplier applied to the
test load of the pipe.
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TECHNICAL DESIGN GUIDE Section 1: System Design
Image to the left: As concrete pipes form part of the load-bearing pipeline structure, a number of alternative bedding types are available. Taken from Technical Design Guide - Section 1.2 Structural Design, Figure A3: Types of bedding.
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