Heavy rains and spring run-off cause the river to rise and wash away the subgrade from beneath the revetment and the road bed. The bridge approach had settled up to 13 inches.
The 8 rows of 3’x3’ concrete revetment were tied together with 1” cable. The cable ran through the road bed to connect with revetment on the other side of the road. The revetment would have to rise up the embankment as the bridge approach lifted.
The bridge approach was lifted an average of 8.5 inches with a maximum lift of 11.5 inches at the lowest point.
PEAK WELD SHOP – DEADHORSE, AK
- Original Building + an Addition = approximately 13,000 sq. ft.
- Walls/Ceiling Height = approximately 25 ft.
- The facility is used to repair and maintain various heavy machinery used on the Alaskan oilfields.
PEAK WELD SHOP FLOOR LIFT
The slab began settling in the early to mid 1980’s due to the melting of the underlying permafrost. By the time the lifting and underpinning project began – total settlement was over 24” in the middle of the slab.
Sections of steel beams were welded to the bottom of columns and hydraulic jack were used to keep the roof from collapsing. Piling supporting the floor also had settled and would have to be lifted along with the 12 inch thick slab. The lift plan included the incorporation of push piers (mirco-piles) for point loads at piling locations.
- Perimeter Settlement = 0 inches
- Settlement measurements were taken using a zip level in 10 foot increments from the perimeter to the middle.
- 10 ft. = 7 in.
- 20 ft. = 12 in.
- 30 ft. = 15 in.
- 40 ft. = 19 in.
- 50 ft. = 26.5 in.
PUSH PIER DRIVING
Push piers were places 4 per pile to insure their movement.
Once the piling were free the leveling and underpinning was done with close cell polyurethane.
- Average final driving pressure = 7000 psi or 56 kips (56,000 pounds of upward thrust) per pier
- Average pier depth to refusal =18 feet
- Pier driving took 4 days
- Lifting Plan – start with center zone (25” of settlement) & work outward
- Due to the extreme amount of settlement & stress on the slab, some zones had to be lifted in stages – meaning piers had to be locked off & then re-pressured
- Shims used to support columns had to be removed & temporary bottle jacks were installed during lifting process
- Rams were moved several times from zone to zone
CHEMICAL GROUTING & BRACKET REMOVAL
- Polyurethane expansion foam was injected after slab lifting for void filling & to slow further settlement
- The lift was completed using the foam lifting process to insure material complete void fill and underpinning of the slab.
- The shop stayed fully functional during the entire lifting process