8197955856

with what is going on here. If we limit the Conference to just, so to say, very technical aflairs we do not give the oppor-tunity to the engineering profession to get acquainted with us; I guess we are not on the right road.

Le President : It is fairly elear that the generał feeling is that so far as it is possible we should not restrict; but, of course, if the situation shows signs of getting out of hand then we can consider it again.

Now we come to ąuestions dealing with sub-committees.

Point 9 — Proposition pour la creation d’un Sous-Comite

charge des facteurs de securite

M. J. Brinch Hansen (Danemark) : In my opinion the ąuestion of factors of safety in soil mechanics is one of the very few subjects that is suitable to be dealt with by a sub-committee. I wish to point out that I do not propose that this committee should fix the actual figures of safety — that would indeed be harmful — but I do think it would be a good clarification if some accepted rules or definitions of factors of safety and the way of introducing such factors in our calculations of failure problems would be good. Thereforc 1 propose that we form such a sub-committee.

Le President : Again I am going to cali immediately for any comments.

M. O. Moretto : When I first heard about the proposal of having a sub-committee on factors of safety I felt very much in favour of it, because, as you all know, all the refine-ments in our calculations are drawn somehow through the factors of safety, which up to now are only derived from what I would cali unqualified experience. But thinking it over morę carefully and relating this problem to the work that has been done in other fields of structural engineering, like reinforced concrete and Steel, I see that the work of this body would be very difficult, and I have strong doubts whe-ther it would be able to come to anything concrete.

I am not talking against a committee: I just want to ask you to be very careful before deciding anything, because we might get into troublesome waters. I am surę that every-body is conscious that, first, the factors of safety in earth work are lower than the ones being used in other branches of structural engineering. As a matter of fact I always find myself in trouble to explain to my students why the factor for an earth dam is only 1.5 maximum while when designing reinforced concrete structures, of which we know much morę, we take a factor of safety which is about 2. In concrete we can control every step of the construction and we can control with sufficient accuracy the properties of the materiał we are using, while in soils the uniformity of the properties of the materiał will vary tremendously from one place to another.

So I think the sub-committee, if it is established, should be concerned exclusively with generał rules — and only generał rules — about this factor of safety, without giving any specified figurę on the numbers to be used in determining the stability of any type of structure.

M. Brinch Hansen : That is what I said.

M. A. Kezdi (Hongrie) : I am in favour of what Prof. Brinch Hansen has said, for a committee on factors of safety, because when once we settle the generał principles we can start on numbers too. I am in favour of Prof. Brinch Hansen’s proposal.

M. K. L. Rao : This is one of the very serious suggestions which we should very carefully consider. The factor of safety means the finality of things, and as a designer I deal with this factor of safety almost every day, and it varies widely depending on so many factors, even for earth dams. It can vary from the one place to the other, depending on extran-eous factors, even for stability for slope the factor can vary from 0.59 to 1.2. Therefore I would say that it is the domain of the designer to take the factor of safety he wants, and what it should be. 1 would say that before any committee should be cven thought of what we should do, if people are really interested in this, is cali for a symposium on this and find out the practices in various countries actually being used, then when we see whether there are any methods which are common we can find something which is common to all. Otherwise, to fix a safety factor is the most dangerous thing anybody can do in a situation like ours.

Le President : We should make it perfectly elear that there is no proposal to fix any values of factors of safety. The proposal is simply to discuss, and if possible to agree upon, the methods of calculating factors of safety in a given case: for example, stability of slope. My own feeling is that this is a subject which is perhaps better left to grow on its own account, and we may find ourselves coming into agree-ment as the problem is morę fully understood. I think a sub-committee might perhaps force the issue, which would not actually be a useful thing to do. In effect we will ultimately be using the same, or very similar, methods when we get to the point of appreciating all the problems involved and we can see what are the correct methods. If that should happen we shall not need a committee.

I will take a quick vote on this. Those in favour of a committee.

M. J. Brinch Hansen : May I change the proposal? I propose, instead of having a sub-committee, having a section on factors of safety at the next International Conference. This idea was given to me by Rao.

Le President : That is to say it either becomes a section of the Conference or at least has a symposium arranged at the ncxt Conference? I think everybody seems to be agreed to that? (Proposition adoptee.)

I take it Mr Legget has noted that? Thank you.

Point 10 — Datę de presentation des rapports des divers sous-comites

Le President : I am going to save time by saying that this item is a proposal by Mr Townsend that a datę for the presentation of sub-committee reports be fixed at nine months in advance of the Conference. I think that his own suggestion of six months I would modify very slightly, and make it nine.

I am very much in favour of this. We cannot actually force the sub-committees to do this, but it is to be strongly encour-aged, by means of a resolution by this Committee, that there should be a report submitted nine months before the Conference. That would be a great advantage, in so far as the national committees would then have a chance to see and study these reports, so that they can come prepared to the main Conference and vote knowingly on these things, rather than having to make quick decisions — which I am afraid is what we had to do this time.

I would propose, therefore, that we make a recommend-ation that sub-committee reports be submitted nine months before the datę of the Conference. (Vote a rnains levees.) (Proposition adoptee.)

Point 11 — Aide financiere aux sous-comites

Le President : Mr Kallstenius, who (as you know) is now Chairman of the new sub-committee on sampling, is raising the generał question of financial aid. May I answer

82

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