Yorkville enquirer. [volume] (Yorkville, S.C.) 1855-2006, 1910-01-04
Mistsllansuus &sadins..
UNDER THE ANDES.
The Tunnel Broken Through at
Last.

lantic with the Pacific coast of South
America between Buenos Ayres and
Valparaiso will probably be completed
next year. The tunnel through the
Andes, which will abolish the gap of
| fifteen miles that now exists has been
broken through, and it should be pos
sible to run a train through by the
the tunnel is the same as that of the
Simplon tunnels feet ga inches
headway above rail level, with a width
Of 16 feet 5 inches at the greatest
arch and side walls is foot Z 3-4
inches thick. The whole, when fin
ished, will be 10000 feet long, in
cluding two artificial ends, together
the highest point will be 1O,350 feet
above the sea. The works at the Ar
gentine end were begun in October,
1905, and those at the Chilean end
some little time earlier. They were
|inaugurated by the Chilean Trans
Andine Contraction company, which
continued to carry on such work as
work at the Argentine end on Feb,
was done until the present contrac-
tors, an English firm, took over the
10, 1908. At that time $50 feet had
been excavated on the entrance curve
to full section, together with direc-
tion gallery 2S0 feet long, on the
through line Of the tunnel. Both
tunnel and gallery had been timbered,
but both had partially collapsed,
water was entering in places and the
works were in a dangerous condition.
On December l, 1908, the English
company took over the construction
Of the Chilean end, where the work
was further advanced.
The top Of the mountain range
through which the tunnel has been
driven is composed of stratified rocks
tilted to high angle. The dip varies
continually, and some Of the strata
are almost vertical. AS in all parts of
the crest of the Andes, the rocks are
subject to extreme weather conditions.
Owing to the constant percolation Of
melting snow, decomposition con-
tinues to great depths below the sur
face, especially along the planes Of
stratification and the assures. The
rocks cut in the eastern half of the
tunnel are chiefly limestones, with
beds Of gypsum, layers Of sandstone,
with some narrow clay bands, as If
along the line Of faulting, and some
beds Of conglomerate full Of very
hard, rounded, water-worn pebbles
and small boulders. Especially near
the mouth all the joints and assures
are so decomposed that the rocks
were found very loose. Even under
the crest of the mountain, with some
1000 feet Of strata overhead, the
decomposition Of the fissure planes
caused by percolation Of water can be
observed in places
At the western end of the tunnel
a change takes place, and the rocks
become mainly feldspathic, with beds
Of hard, tough clay. in veins. These
stand much better than those of the
eastern side, but there are very many
joints and cleavage planes. The
western side Of the mountains are
sleeper in slope than the eastern, and
the rocks are Of different series and
much more solid. Some of the rocks
when thrown on the tip weather very
rapidly; others stand very we'll where
the stone is solid, but give way quick
ly in the joints. 1t has. therefore,
been necessary to line the tunnel
throughout, for, while many Of the
rocks may in themselves stand the ex-
tremes of heat and cold, no depend
ence can be placed on any of the
cleavage planes.
The work was begun at both ends
with a top heading excavated to a
size of seven feet by seven feet.
When the English firm took over the
work at the eastern end they alter
ed the construction and drove the
heading 10 feet wide and 10 feet high
from the floor level Of the tunnel. A
metre gauge line carrying wagons Of
a capacity Of 4 cubic metres was run
into this heading and the entire ex-
cavation Of the arch and much of the
sides was broken from overhead, the
excavated materials being allowed to
fall into the railway trucks below. At
the western end the excavated ma
terial was run out to the tip in small
trucks hauled by mules.
The manner of working the exca-
vation to put in the concrete lining
was to break out the arch to full
width down to its springing, and then
to eXcavate the main block of the
lower excavation that remained on
each side of the three metre by three
metre bottom heading, shoulder be-
ing left on each side wide enough to
carry the centring. When the cement
in the arch was sufficiently set, the
centring was removed and the arch
stood on the shoulders, which ulti-
mately were broken back to the full
size of the tunnel, side walls being of
in under the arches. In the bulk of
the work the arches were so fast to
the rough crown of the tunnel as to
need no undepinning; but where the
strata were soft or loose, they were
underpinned until the shoulders were
removed, and the concrete side walls
were completed. The concrete for the
lining was mixed six to one, and
stone, gravel and sand of fine quality
were got from the river just outside
Of the tunnel works.
The labor was Italian, Argentine,
Spanish and Chilean, some 1900 men
having been employed for four years.
The work was carried on continuous
ly in eight-hour shifts without stop
pages for Sundays or holidays; but
on these days the men were paid time
and a half
When the railway is completed, the
journey from Buenos Ayres, on the
eastern side of the South American