Moncrief Army Hospital
Situation: The ground floor of the Moncrief Army Hospital had settled a maximum
of six inches. The ground floor was constructed as a conventionally reinforced
slab-on-grade floor over 25 to 30 feet of fill soil. The settled portion
of the floor slab was to be removed and replaced with a new floor system.
The new floor slab was to be a partial structural slab with a lower level
for additional mechanical units and a slab-on-grade for the remaining
area. Except for the designated work area, the remaining areas of the
hospital were operational and could not to be disturbed by the noise or
exhaust fumes from the machines required to perform the underpinning work.
All piles were required to penetrate the fill soil and have a maximum
allowable deflection in tension and compression of 0.25 inch.
Solution: Fifty-nine Ram Jack helical piles with an allowable 30 kip capacity in
tension and compression were required to resist the required loading.
Twenty-nine of these piles were battered at 30 degrees to resist the lateral
loads. Pile load tests were performed to verify the capacity and deflection
limits of the piles in both tension and compression. All testing was monitored
by the Corp of Engineers and independent consulting engineers. The equipment
was carefully chosen that wouldn’t exceed the noise or exhaust limits
established by the Corp of Engineers and the hospital but still have the
power to install the piles to the required capacities. The noise and exhaust
fumes were constantly monitored throughout the underpinning operation
by the Corp of Engineers. The safety limits of the noise or exhaust were
never reached which would have required stoppage of the work or evacuating
portions of the hospital.
Conclusion: With the stringent performance criteria, Ram Jack is one of the few systems
with the expertise and installers to perform such a sensitive project.
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