Shoring:
Helical Soil Screws vs Grouted Soil Nails
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In the right soil conditions, helical soil screws can be a great alternative to traditional grouted nails for temporary or permanent shoring projects. These screws can provide stand alone shoring or be integrated into other lagging / sheet pile systems where lateral support is necessary.
SOIL SCREW
Underpin existing structures at top of excavation if necessary
1
Excavate first lift of shoring
2
Helical soil screws develop immediate loading of the shoring system unlike grouted nails which can take 3 days to develop resistance. This means no down time due to curing of grout which keeps your project moving forward.
FAST INSTALLATION
Install soil screws on typical 5 ft on center spacing
3
For shoring that is capable of a 1:4 slope, the excavated area is covered with geofabric cloth and welded wire fabric. A plywood washer, steel plate and termination adapter are attached to soil screw and final load is applied.
Flexible Face Option
Install geofabric over excavated cut leaving 12 inches additional fabric to overlap at all joints and next cut
4
Install 4 x 4 welded wire fabric, leaving minimum of 2 squares at base of excavation to overlap wire on next cut
5
For shoring that requires a vertical cut, the excavated area has drain tile installed on every other column and is covered with welded wire fabric. Shotcrete is applied to the wall a minimum of 4 inches thick. Steel plates can be added prior to or immediately after shotcrete application.
Shotcrete Face Option
4 inches of shotcretefor temporary shoring,6 inches for permanent
6
Excavate first lift of shoring
2
Soil screws are not applicable for all soil conditions. For extremely hard soil / rock or large projects where grouted nails are more cost effective, CFS utilizes grouted nails that can be installed in any soil condition.
Soil Conditions
Underpin existing structures at top of excavation if necessary
1
Excavate first lift of shoring
2
Fast install, immediate loading of soil screw, less equipment to mobilize for tight job sites, no spoils (good for brown site projects)
pros and cons
Underpin existing structures at top of excavation if necessary
1
Excavate first lift of shoring
2
Not able to install in all sites, can be more costly than grouted nails on larger projects
pros
CONs
Soil SCREW
Can be installed on any site and in any soil condition, more cost effective on larger projects
3 day cure time for grouted nails (no instant loading), more equipment to mobilize (larger footprint)
pros
Soil NAIL
CONs
Let CFS assist you in determining which system
would be the most cost effective for your next project
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