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Matthias, F. T. (ed.) / The Wisconsin engineer
Volume 33, Number VIII (May 1929)

Soroka, Mary O.
Underpinning the Mutual Life Insurance building,   pp. [277]-278


Page [277]


91ieaWISCONSIN
      ENGIN EER
Underpinning the Mutual Life Insurance Building
By MARY 0. SOROKA
THE      construction of the
T    Nassau Street Subway in
New York City necessitated the
underpinning of many inter-
esting buildings. A typical ex-
ample of present day practice
in underpinning tall buildings
along the Route is that of the
Mutual Life Insurance Build-
ing, designed in 1883, and
occupying the entire block
between Cedar and Liberty
Streets. Rising straight from
the street level, its walls pre-
sent a fluted surface which
relieves the monotony of the
abrupt geometric faces of mod-
ern skyscrapers surrounding it.
The solid brick piers below the
street level conform with the
wall surfaces above, receding or
projecting meticulously with
them.
   The exterior walls and foot-
ings, of the sound and sub-
stantial construction of their
period, have remained intact
notwithstanding the deep cais-
son foundations of the Chase
National Bank and the Equit-
able Building nearby.  Street
walls are brick faced with
granite. Although the building
is only 9 stories high, the pier
  oads average 400 tons, the
Showing Underpinning under Times Building and
protection wall under Tribune Building during Nassau
Street Subway Construction.
center piers, about 565 tons
each. If this building were of
the steel skeleton type, the
loads would be cut just about
one-half.
  Eleven feet below the street
is the basement floor, which is
surrounded by an areaway ex-
tending from the Building Line
to the edge of the sidewalk and
making an underground pas-
sageway around the three street
faces of the building. It was
possible through the use of
this enclosed space to underpin
entirely from the outside of the
building.  The entrance for
workmen was through a side'
walk elevator opening on Nas-
sau Street. Construction ma-
terials were delivered directly
from the street almost daily.
Pumps were installed here as
well as a large settling tank
used to filter the sand from
the mud hog pump discharge.
The areaway wall, two feet of
solid brick, was left undisturbed
throughout the underpinning,
the subway heading to the
south remaining in the vicinity
of Wall Street, and that to the
north, several feet away from
the wall. Eventually it will
be removed since the neat line


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