On Fri, 7 Nov 2003 22:53:32 -0000, "iantheengineer"
wrote:



As an engineer I do know that many fundamental principles can be applied to
many different materials, however what isnt being accepted is that different
problems require different solutions and the same principles do not apply to
all things, Steve seems to think that all problems can be solved through
increasing capacity, which they can be solved, but at what expense???,
however he is not considering the problem from all aspects to increase
conveyance is only one way of solving the problem. I am by original training
a drainage engineer and for many years (before my time) the only solutions
to drainage problems were to increase the conveyance or capacity of the
system. This has resulted (along with different rainfall patterns) in the
floods that we experienced in 1998 and 2000. Engineers now look at this
problem more holistically looking at the source of the rainfall and how it
runs off the ground, in an attempt to attenuate the flow to more greenfield
states.

We cant as yet at least prevent rainfall falling at high intensity during
the summer months and for long durations during the winter months, but we
can slow its journey to the river system and reduce the peak flows in the
river.

Unlike rainfall we have another alternative with traffic we can restrain the
source if we choose, which along with the other tools including where
necessary road building will help the road system cope with the traffic.

As for your example of stones deflecting well thats a new one on me.
Subsidence is due to the mines or other underground tunnel etc gradually
collapsing and what normally happens is failure of the foudation leaving a
crack visible in the supported wall either through the blocks or the mortar
joints whichever is the weakest. Stone and concrete are strong in
compression but weak in tension so as you get a force acting on one side
causing compression in one face through bending, you get tensiile forces on
the other face which normally resulst in cracking and subsequent failure. I
daresay that stone will deflect to a degree but this would be unmeasurable
to the naked eye.


Professor Unwin, I assure you that around here I can show you stone
(most likely millstone grit) walls that have deflected (The stones
have bent it's not that the all the motor joints have broken and the
wall is just a collection of stones in formation) by about an inch in
a 5 foot run under their own weight and the weight of the stones above
them.

DG