WOLF CREEK PASS CORRIDOR
TUNNEL AND ROADWAY
SH 160/Wolf Creek Pass, Colorado
Lyman Henn provided complete design and
construction inspection services for an eight mile long section
of the the Wolf Creek Pass Project on Highway 160 in Colorado .
The project included a 908-ft long two lane tunnel and extensive
sections of rock cuts up to 200-ft high, soil nail retaining walls,
boulder walls and mechanically stabilized earth (MSE) walls. In
addition, challenging foundation conditions required deep foundations
below some of the wall structures.
The Upper Narrows Tunnel
provides two traffic lanes in a bi-directional configuration and
was excavated through volcanic tuff bedrock. Excavation was accomplished
using drill and blast methods in multiple drifts, with rock bolts
and shotcrete for initial support and cast-in-place concrete final
lining. The tunnel also has safety and life support systems including
emergency egress adits, a ventilation system, lighting, and monitoring.
The major rock cuts and ground
nail walls in close proximity to the existing highway were constructed
in an environmentally and visually sensitive setting. Lyman
Henn designed the geotechnical parts of the project. Specific tasks
included design of rock cuts, reinforcement and rockfall mitigation
that were visually acceptable to the U.S. Forest Service. Lyman
Henn provided field engineering support including consultation on
rock blast designs, recommendations for scaling and rock bolting
of cut faces, observation of ground nail wall construction, and
oversight of field testing for rock bolts and ground nails. During
construction, Lyman Henn also worked with CDOT and the US Forest
Service to improve the visual appearance of the rock cuts by eliminating
half-casts and using rock staining.
The project also included highway embankments over 40-ft high. Slope
stability analyses were performed to evaluate slopes steeper than
2H:1V. Some of the embankment sections required the use of MSE retaining
walls due to the limited right-of-way. |
|
