HYDRO31020

• Permit No: M1977342
• IBM Index Class Name: Hydrology
• Doc Date: 11/3/1986
• Doc Name: RESEARCH SOIL ANALYSIS
• Media Type: D
• Archive: No

Unique invert and rail-laying for mine tunnel
ENGINEERS ON a long Colorado
mine tunnel have devised a time-
saving system for building invert and
laying rail. The concept is enabling
the project managers and contractor
to reach two major objectives: 1)
completion of the invert and laying
of the hvo-track rail system almost
simultaneously, and 2) meeting tight
specifications for final rail tolerances.
The tunnel is a 914-mi. bore into
the Rocky Mountains of northern
Colorado. It is part of a $500-million
molybdenum mine development by
A\-1AX Inc. Drano Corporation of
Pittsburgh, f a., earlier drove sis mi.
of the tunnel under a negotiated
contract. It is now building the in-
sert and laying rail for the ore
trains. The contract also calls for
installing the permanent drainage
system and electric train control sys-
tem.
The problem is that this is a dcad-
end hmnel, ending at the ore de-
posit 9k mi. inside the mountain.
Placing the concrete would of neces-
sity begin inside and work ouhvard
to the portal. The schedule could
not perrnit waiting until completion
of the concrete work and then in-
stallation of the rail, yet passing
rail through the concreting opera-
tions seemed like a dfsnrptive and
time-consuming prospect.
Project engineers and the con-
tractor working together solved the
problem by re-thinking the whole
seyuence and juggling it around.
They got the roil inside the tunnel
first, placing it temporarily along
both sides of the tunnel on preci-
ously placed concrete curbs. There,
it wasn't just out of the way so that
the invert operations could move
through, but it could also sen~e as
running rail for the paving train.
After concrete had been placed, it
was a relatively simple matter to
move it onto the finished slab and
bolt it into place. Rail laying could
follow concrete work by only a few
clays, allowing time for the 9-in. slab
to reach sufficient strength. Or, put
another way, about 10 days after the
contractor reaches the portal with
the rnncrete invert completed, rail
placement will be finished, also. The
system permitted the engineers to
plan both operations independently
and the result is a high rate of pro-
duction for both.
Concrete is tra isported into the
tunnel in hvo-car trains, using 6-yd.
1\toran agitator errs with a total
payload of 12 yd The concrete is
angered out of the end of the car
and onto a conveyor system and
from there to a 13,'4-ft.-wide screed.
Instead of letting the pre-laid rail
lie idle nn the cr rb alongside, the
entire paving train was mounted on
it to obtain a smoath-moving open
tion and make possible the precise
rail positioning de~randed. In mm~ing
his eyuipment dmvn the rails, the
contractor is off the uneven tunnel
Hoor completely and on a firm base
for placing and finishing the con-
crete. Thus, the system is insuring
another tough requirement, that the
invert concrete be finished to close
tolerances and rail placed to within
;rth in. in 30 ft.
PAVING TRAIN rides on rails }ha} ul}ima}ely were moved info posi}ion an }he invert }o serve as }he }rack Fer }he ore }rains.
Parallel grooves were for fhe elec}rival sys}em }o power }he }rains.