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Jobs Done Well.
Kiewit Underground is a leader in the tunneling industry. Headquartered in
Omaha, Neb., we construct underground facilities across the U.S. and Canada.
We have proven tunneling experience with a variety of tunneling and excavation
methods. Our drill and blast projects include:
Drill and Blast
Lake Hodges Tunnel
The Lake Hodges Tunnel consisted of a 5,850-foot-long, 12.5-foot horseshoe
tunnel excavated, using controlled detonation drill-and-blast methods. The tunnel
was excavated along a continuous slope starting at 2 percent and proceeding to
19 percent. Ground conditions were predominantly a granitic material requiring
pattern bolting for ground support. Instances of shear and fault zones required
additional mine straps. Primary tunneling equipment included a drill jumbo and
tunnel muckers. A detailed seismographic program was initiated to continually
monitor any effects of blasting to existing residences and facilities.
Harlem River Tunnel
The project consists of two 165-foot-deep circular shafts connected by a
675-foot-long horseshoe tunnel directly beneath the Harlem River. Bedrock in this
part of Manhattan is white marble and found at a depth of about 70 feet below
grade. Overburden at the shafts is a mix of sandy and silty soils with support of
excavation in the overburden being secant pile walls. Once in rock, conventional
drill-and-blast techniques were used. Initial rock support consists of 9-foot-long
swellex friction bolts and shotcrete in most areas, with 15-foot-long swellex bolts
being used in the soil/rock interface and turn under areas. Primary tunneling
equipment included a drill jumbo and tunnel muckers.
The Richland Creek tunnel consisted of a 5,700-foot-long tunnel 8 feet in diameter between two shafts. Controlled detonation drill-and-blast tunneling method was used for 4,300 feet of hard rock consisting predominately of 33-ksi gneiss. Both jacklegs and a drill jumbo were used for blast hole drilling in the small diameter tunnel heading. Tunnel spoils were hauled with small locomotives and muck cars. Ground support for the tunnels was provided a combination of steel sets and rockbolts.
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