TIEBACKS
One of America’s most accomplished design-build contractors, Schnabel creates excavation support systems and anchored retaining walls by using tiebacks to provide reliable lateral resisting force.
Tieback construction bolsters an excavation support system or retaining wall by anchoring into the soil behind an excavation. Tiebacks are similar to tiedowns which provide vertical support to a foundation to resist hydrostatic uplift, wind and seismic loads.
An innovative nationwide earth retention and specialty foundations construction company, Schnabel has the expertise to provide you with dependable excavation support systems and anchored retaining walls.
TIEBACK SOLUTIONS
Tiebacks are used to provide the lateral resisting force for many of the excavation support systems and anchored retaining walls that Schnabel builds. They are constructed by grouting a high strength steel bar or strand bundle into the soil or rock behind the failure surface of the retaining wall. After the grout has cured, every tieback is tested, and the load is locked in to limit movement.
In addition to their use in the construction of new retaining structures, tiebacks are also used to stabilize existing anchored retaining walls that are moving or deteriorating. Schnabel has patented systems for the tieback connections and facings used for the repair of distressed MSE, Bin and cantilevered retaining walls and has specialized equipment for drilling tiebacks through failing bulkheads along the waterfront. Tiebacks are also used to stabilize landslides where the tieback can be anchored in the soil or rock below the slide failure plane.
Tiebacks can be used for both temporary and permanent applications. Permanent tiebacks differ from temporary tiebacks in that the critical components of the tieback tendon and anchor head are protected from corrosion. Tie back construction can be anchored into most types of soil and rock. The capacity of the anchors in soil will vary depending upon soil type and installation method. Denser, granular soils will typically produce higher capacity tiebacks. Schnabel has installed tiebacks with lengths in excess of 200 feet and tested capacities of over 500 kips.
A slight variation of the tieback is the tiedown. The construction is similar, but the direction of the force is primarily vertical rather than horizontal. Tiedowns are used to resist hydrostatic uplift on structures built below the water table, seismic loads created by earthquakes and uplift forces caused by wind loading on a building.
To learn how Schnabel can provide you with reliable excavation support systems and anchored retaining walls, please contact one of our regional offices.
Sub-surface to street level, safely and efficiently.
TIEBACK CASE STUDIES
St Jude Outpatient Clinic & Clinical Building | Memphis, TN
Flintco LLC contracted with Schnabel to design and construct the shoring required for two 15-story buildings. The shoring scope consisted of approximately 3,000 linear feet of excavation support, primarily ranging in height from 15 to 29 feet, and featured 311 soldier beams, 236 tiebacks, and approximately 50,000 square feet of wood lagging.
Red Rock Hydroelectric Facility | Des Moines, IA
Schnabel was the Tieback Anchor Contractor for this award-winning project and installed 153 post-tensioned tieback rock anchors up to 173 ft long. The tieback anchors helped support a large 60-foot tall temporary secant pile wall that was positioned above a 40-foot-tall rock cut to allow for the construction of a new powerhouse on an existing flood control dam.
The key to success on the Port of Houston project was having the right equipment to reach up and install the tiebacks. Our engineering design eliminated the need for walers which really helped the schedule. Encasement of the anchor heads in concrete was critical to the long-term corrosion protection of the tiebacks especially in the marine environment. Forde Construction planned and coordinated the project exceptionally well so the work could be done safely while not disrupting the vital truck and railroad traffic flow at the very busy Port of Houston.
The Port of Houston was an exciting project that demanded continuous attention to detail. At some sections of our tieback walls, rock was encountered at a higher elevation than originally considered. To keep the project moving, Schnabel collected and reviewed data on a daily basis, then updated our design as needed in preparation for the next day’s operations.
