COLTON—A BIT OF EXPERIENCE WITH PILES IN CHICAGO.        13

A BIT OF EXPERIENCE WITH PILES IN CHICAGO.
 

By Simeon C. Colton, '85, Civil Engineer, Chicago.

When driving the piles for the foundation of the Edison Light
Co.'s Power House, corner of Harrison street and Chicago river, the
representative of the architect of the building expressed a doubt as
to the efficiency of a steam pile hammer. To settle this point three
test piles were driven as described below.

Pile No. 1, 50 feet long, was driven with a drop hammer weigh¬
ing 3 600 pounds.    The sinking was as follows:

8 feet 0 inches in 10 blows of  6 feet each.

6   "   0     "       '' 10     "      "    6    "     "

6   "   6     "    • " 10     "     "   10   "     "

2    "   3     "       "4     "     "  15    "     "
4   "   0     "       " 10     "     "   15    "     "

3    "   5     "       " 10     "     "  20   "     "
1    "   9     "       " 10     "     •'  20   "     "
1   "   7     "       " 10     "     "  20   "     "

Bearing Power by Baker's formula* = 20 tons.

"           "      "   Engineering News formulaf = 25 tons.

Pile No. 2 was driven with a steam hammer, the total weight of
the hammer being 8 100 pounds and that of the striking weight
3 500.    The stroke was 32 inches.    The sinking was:

5 feet in 15 blows.
 

5
3
2
1
1
1
1
0.62
 

19

28

31

19       "

20

25

20

19

s formula::=10.0 tons.
 

Bearing Power by Baker'j

"           "      "   Engineering News formula=6.7 tons.

Pile No. 3 was driven with same hammer as No.  2.    The rate

of sinking was:

8 feet by weight of hammer alone.

12    "   in   23 blows.

3     '•     "   18

3     "     "   27

3     "     "   40

2     *'     "   40

0.5  "     "   10       "

Bearing Power by Baker's formula = 7.0 tons.

"           "      "   Engineering News formula = 6.2 tons.

After standing over night the sinking of pile No. 3, under the
drop hammer, was:

0.4 inch for fall of  2 feet 8 inches.
1.6    "     "     "   '^15   "   0
______________________1.7    "     ''     ''   ''20   ''   0   .   "________________________

^Baker's Masonry Construction, p. 239.
tEngineering News, Vol. 22, p. 373, (Oct. 19, 1889.)