A Self-Learning Manual - Institution of Engineers Mauritius

A Self-Learning Manual
Mastering Different Fields of Civil Engineering Works (VC-Q&A Method) Vincent T. H. CHU
Fig. Match soffit VS match invert
2. Should precast concrete pipes be laid with spigot pointing
downstream direction when fitted into sockets? (DD2)
There is a general rule of laying precast concrete pipes: the precast
concrete pipes should be laid from downstream end to upstream end.
Moreover, precast concrete pipes should preferably be laid with spigot end
pointing downstream direction when fitted into sockets.
The reason of laying pipes from downstream to upstream is that any
rainfall occurs during construction can be drained off the site without
flooding the pipe trench. Moreover, gravity and other forces applied to the
pipes during installation of pipe joints help tighten the joint and eliminate
any remaining joint gap. On the other hand, for pipe laying with spigot point
downstream direction, this prevents the joints from opening up arising from
pipeline movement. The concrete pipe joints are also protected from the
entry of foreign materials.
3. Which shape of drains is better, elliptical or circular? (ED1)
Horizontal elliptical pipes are commonly used where vertical clearance is
hindered by some existing structures. Moreover, horizontal elliptical pipes
possess higher flow capacity for the same flow depth than most other
structures with equivalent full capacity.
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