19 June 2001
REINFORCING TIE-BACK SYSTEM FOR TIMBER SHEET PILING
Problem: Light to moderate movement of the top of the timber sheetpiling wall
has occurred due to tie-back failure or excessive loading behind the wall. The
area behind the wall is accessible to perform repairs.
Description of Repairs: Install a new wale slightly above the existing wale.
Locate the new deadman anchors based on engineering calculations. Trench for
the tie rods between the wall and the deadman anchors. Place the tie rods
through the wale and sheet piles and secure in place to the deadman anchors
(see Figure 6-9). Install zinc or magnesium packaged anodes to prevent further
corrosion of the rods.
Replacing an existing tie-back system may involve replacing any or all of the
existing components, depending on the amount of deterioration that has taken
Sheet pile wall movement can also be arrested by changing the soil load acting
on the wall. For example, stone riprap dumped against the exterior toe of the wall
will add resistance to the movement of the toe. Alternatively, or in addition,
backfill can be removed from behind the wall and replaced with lightweight
granular fill. This type of fill frees drains, which reduces the hydrostatic pressure
behind the wall and allows the water level on both sides to balance.
Application: Reinforcing or replacing the tie-back system may be restricted to
correct slight to moderate wall deflection. Excessive deflection may require
replacing the wall or major restoration. With timber construction, it is unlikely that
excavation and pulling the wall back into position can be done without high risk of
failure of the timber members.
Future Inspection Requirement: Pay careful attention to wall inspection for
further signs of continued deflection or timber member failure.