Arizona republican. [volume] (Phoenix, Ariz.) 1890-1930, 1902-04-27

square foot; authority. j. T. Tanning.
p. -.O3.
ST. Peters. Rome; material caIcar-
eGuS ufa; pressure, 49, tons per squire
foot; authority, J. r. flaming. p. 4Oa
Various arch bridges: material. eat
masonry: pressure, coo tons per square
! foot: authority, J. T. Tanning. u. 403.
Quaker bridge dam projecteO; ma
te1ial ruDbie masonry; pressure, $50
tons per square foot; authority, Rep.
Acqueduct Com, p. So.
Almanac dam 600 years old; ma
terial, rubb!e masonry; pressure, 14.S
tons per square foot; authority, Ed
ward WeSman, p. "a.
| VARIOUS EXPERIMENTAL TESTS.
Material crushed
1-Concrete prisms cut from Vrynwy
| dam; pressure. ISL tons per square foot;
authority. Sir andrew Clark.
2-Granite ashlar. with moree..---22;;
pressure, $50 tons per square foot; au-
| thority. Austrian Society E. &, a.
| 3-Sandstone rubble, mortar 1:2;
pressure. $50 tons per square foot; au-
thority. Austrian Society E. & a.
! 4-Sandstone rubble. mortar 49,;
pressure. 1874 tons per square foot: au-
thority. Austrian Society f. d A.
| 5-Gravel concrete 1.2:3; pressure, 1913
/ tons per square foot: authority, Aus
! tlian Society z. & y.
| 6-Gravei concrete 1875; pressure. &C
! tons per square foot; authority, Aus
/ trian Society e. x \.
| Two cubes Of one cubic inch each
were cut from briquetts OF neat ce-
ment. manufactured from materials
| obtained near the site. These We're
tested at the L. s. navy yard in Wash
! ingtOn.
Sample l crushed at $3.50 pounds or
So tons per square foot.
Sample No. , crushed at $50 pounds
or S35 tons per square foot.
Two cubes with edges of two inches
were cut from samples of the rock to
be used in Salt river dam and crushed
in the testing machine at the L. s.
navy yard in Washington.
Sample No. ! crushed at 50, $50
pounds. being 14.912 pounds per square
inch. or 1914 tons per square foot.
Sample No. crushed at 10000
pounds, this being 1860 tons per square
foot. These results are so high that
the strength OF the rock is entirely
eliminate from the discussion.
/ Test No. > in the above table, mad .
by the Austrian Society, is very nearly
representative OF the masonry to be
used in the proposed Salt river dam. a
coefficient of safety of ten in such ma
! Gonry would permit of pressures of over
% tons per square foot. AS Will appear
| later the maximum pressures permitted
| in the proposed dam viii be far below
this figure.
The recorded failures of high ma
sOnry dams are as follows:
l. Habra dam in Algiars Poor hy-
draulic lime was used and a red earth
with d large percentage Of clay was
used in the mortar instead of sand
This combination made a poor mortar
and the rock was also poor. both in
the masonry and the foundation. being
4 calcareous grit of varying quality
and all porous. 1t is supposed that the
failure occurred by the crushing of the
foundation under computed stress OF
IS $40 tons per square foot.
>. BCuzy dam in France. The foun-
dalton was assured and permeab bic. and
not on solid rock. allowing an immense
upward hydrostatic pressure: the sec.
ten was 50 light as to permit great
tension in the masonry in the back I
was straight in plan and when the res
ervoir was nearly filed the central por-
ton Of the wall was showed forward
about a foot, causing ruptures ant
leakage. This vas afterward repaired
and the foundation reinforced. Sly
years later when the reservoir was full
the dam suddenly overturned at :
plane about SO feet below the top TIL,
above recited defects were the un
/ doubted cause.
5. Puente dam in Spain. The cen
: Of RI,
upon piles driven in earth. When tn,
rising water applied a heavy hydro
; static pressure. this portion of tn
foundation suddenly gave way and lief
, the top and ends of the dam standin.
in the form OF an arched bridge
+. Austin dam, Austin Texas. Thi
was an overflow dam built OF Hmeston,
rubble, the stone being very soft anc
of poor quality. The foundation wa
on geological fault. and was Of sof
limestone in thin, horizontal layers
which had little adhesion, and prob
| ably very little friction upon one an
other, and the failure, which was b,
sliding, is supposed to be due to thi
fact.
In all four of the above cases tn
foundation was defective. In three tn
stone was poor and in two the morta
was poor. All were straight in plan
l except the Puentes, which was poly
gonal in plan. and arched upstream
This dam seems to have been very wei
} planned and constructed, except for tn
one fatal defect of being founded OF
piles.
5 All of the defects in these failure
= can easily be avoided in the propose,
l cam, by reasonable application 0
F., care and skill.
I The proposed dam is designed to b
. 211 feet above datum, which is 10y
= water in the river at the dam site, an
.. to store water at a maximum depth o
$50 feet the total height of dam abov
: lowest foundation being about 245 fee
: Spilways 20 feet deep will be excavate,
IN the solid rock sides of the canyo
= ana the rock used in the construction
OF the dam. The location lends itsel
= admirably to a curved form of dan
: this form containing but little NOR
= material than a straight one of tn