Pressure, Resistance, and Stability of Earth: American Society of Civil Engineers: Transactions, Paper No. 1174, Volume LXX, December 1910Meem, J. C.
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Pressure, Resistance, and Stability of Earth: American Society of Civil Engineers: Transactions, Paper No. 1174, Volume LXX, December 1910
Meem, J. C.
Civil engineering -- Periodicals; Soil mechanics
A more careful reading would have shown Mr. Goodrich that this
concession was one of the writer's as to certain pressures against or on
tunnels, and, if Mr. Goodrich does not concede this, he is even more
radical than the writer.
And again:
"'Nor can anyone * * * doubt that the top timbers are stressed more
heavily than those at the bottom' is emphatically doubted and
earnestly denied by the writer."
It is unfortunate that Mr. Goodrich failed to make the complete
quotation, which reads:
"Nor can anyone, looking at Fig. 5, doubt," etc.
A glance at Fig. 5 will demonstrate that, under conditions there set
forth, the writer is probably correct in his assertion as relating to
that particular instance. Further:
"For instance, the author's well-known theory that the pressures
against retaining walls are a maximum at the top and decrease to
zero at the bottom, is in absolute contradiction to the results of
experiments conducted on a large scale by the writer on the new
reinforced concrete retaining wall near the St. George Ferry, on
Staten Island."
The writer's "well-known theory that pressures against retaining walls
are a maximum at the top and decrease to zero at the bottom" applies
only to pressures exerted by absolutely dry and normally dry material,
and it seems to him that this so-called theory is capable of such easy
demonstration, by the simple observation of any bracing in a deep trench
in material of this class, that it ought to be accepted as at least
safer than the old theory which it reverses. As to this "well-known
theory" in material subject to water pressure, a careful reading of the
paper, or an examination of Fig. 12 and its accompanying text, or an
examination of Table 1, will convince Mr. Goodrich that, under the
writer's analysis, this pressure does not decrease to zero at the
bottom, but that in soft materials it may be approximately constant all
the way down, while, in exceptionally soft material, conditions may
arise where it may increase toward the bottom. The determination should
be made by taking the solid material and drying it sufficiently so that
water does not flow or seep from it. When this material is then
compacted to the condition in which it would be in its natural state,
its angle of repose may be measured, and may be found to be as high as
60 degrees. The very fine matter should then be separated from the
coarser material, and the latter weighed, to determine its proportion.
Subtracting this from the total, the remainder could be credited to
"aqueous matter." It is thus seen that with a material when partially
dried in which the natural angle of repose might be 60 deg., and in which
the percentage of water or aqueous matter when submerged might be 60%,
there would be an increase of pressure toward the bottom.
Public-domain text, read in full here on John Shaqi.
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