19 June 2001
SR-9: REPLACEMENT OF EXISTING STEEL SHEET PILE WALL
: Serious deterioration
of the steel sheet pile structure has occurred;
patches cannot be used for repairs.
Description of Repairs: Two methods are available for replacing deteriorated
steel sheet piling:
Timber Sheet Piling: Remove decking (if required) behind existing steel sheet
pile wall to provide enough space to excavate and drive timber piling. Excavate
to expose tie rods (usually these are above mean low water). Place new timber
wales to act as template for driving timber sheeting. Drive timber sheeting (see
Figure 8-9). Backfill may not be possible between steel sheeting and timber
sheeting below wales. Replace decking (as applicable).
Steel Sheet Piling: Drive new steel sheet piling in front of existing sheet piling.
Drill hole for tie rod and pipe casing through both walls into stiff clay, out of active
zone behind old wall. Pressure grout inside casing forming bulb in clay at end of
casing (see Figure 8-9). Fill space between old and new sheet piling with
concrete. If stiff clay is not available, deadmen may need to be added to secure
the tie rods. Ensure electrical isolation is maintained between the existing and
new sheet piling, especially through tie rods.
: Either solution should stop the loss
of backfill through the existing
steel sheetpiling wall.
The timber sheet piling should be less expensive than the new steel sheetpiling
wall. However, the timber piling will require access behind the existing wall, and
continued corrosion of the existing steel sheet piling can be expected.
The new steel sheet piling can provide a new wall with equal or greater strength;
and construction can be done without excavating behind the existing wall. This
approach does, however, require grouted tie rods be secured in existing soil. If
stiff clay or other suitable soil is not available, this method may not be
appropriate unless deadmen are added.
Future Inspection Requirement: Normal inspection requirements should suffice
for the new steel sheet pile wall. If the timber piling approach is used, more
extensive annual inspections may be required to watch for signs of timber piling