Pressure, Resistance, and Stability of Earth: American Society of Civil Engineers: Transactions, Paper No. 1174, Volume LXX, December 1910Meem, J. C.
Science
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
The writer considers as very doubtful the formula for _D_{x}_, which is
the same as that for _W_{1}_, already discussed. The author's statement
that "additional back-fill will [under certain circumstances] lighten
the load on the structure," is considered subject to modification by
some such clause as the following, "the word 'lighten' here being
understood to mean the reduction to some extent of what would be the
total pressure due to the combined original and added back-fill,
provided no arch action occurred."
The writer is in entire agreement with the author as to the probability
that water is often "cut off absolutely from its source of pressure,"
with the attendant results described by the author (p. 378); and again,
that too little attention has been given to the bearing power of soil,
with the author's accompanying criticism.
The writer cannot see, however, where the author's experiments
demonstrate his statement "that pressure is transmitted laterally
through ground, most probably along or nearly parallel to the angles of
repose," or any of the conclusions drawn by him in the paragraph (p.
381), which contains this questionable statement. Again the writer is at
a loss as to how to interpret the statement that the author has found
that "better resistance" has been offered by "small open caissons sunk
to a depth of a few feet and cleaned out and filled with concrete" than
by "spreading the foundation over four or five times the equivalent
area." The writer agrees with the author in the majority of his
statements as to the "bearing value and friction on piles," but believes
that he is indulging in pure theory in some of his succeeding remarks,
wherein he ascribes to arch action the results which he believes would
be observed if "a long shaft be withdrawn vertically from moulding
sand." These phenomena would be due rather to capillary action and the
resulting cohesion.
Naturally, the writer doubts the author's conclusions as to the pressure
at the top of large square caisson shafts when he states that "the
pressure at the top * * * will * * * increase proportionately to the
depth." Again, the author is apparently not conversant with experiments
made by the Dock Department of New York City, concerning piles driven in
the Hudson River silt, which showed that a single heavily loaded pile
carried downward with it other unloaded piles, driven considerable
distances away, showing that it was not the pile which lacked in
resistance, as much as the surrounding earth.
In conclusion, the writer heartily concurs with the statement that "too
much has been taken for granted in connection with earth pressures and
resistance," and he is sorry to be forced to add that he believes the
author to be open to the criticism which he himself suggests, that "both
in experimenting and observing, the engineer [and in this case the
author] will frequently find what is being looked for or expected and
will fail to see the obvious alternative."
Public-domain text, read in full here on John Shaqi.
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