CETN-III-7
3/81
have cathodic protection or
appropriate coatings to control corrosion in
saltwater.
Timbers should
be pressure-treated with preservatives to pre-
vent rot in freshwater and
fouling and other infestations in saltwater,
especially marine borers in
warm water.
DESIGN CONSIDERATIONS FOR BULKHEADS:
1 . If the bulkhead fronts a beach which cannot be sacrificed, a beach fill
and additional protective structures may be required.
If access to the
beach is desired, stairs over the bulkhead can be added.
2 . Earth pressures on the landward side of the bulkhead are the main
design considerations, but wave forces on the seaward side should also be
considered.
Adequate resistance to the wave forces will be provided by
the landside fill if it is maintained in place. Resistance to earth pres-
sures can be provided by proper design of the bulkhead.
Crib and cellular-
type bulkheads should have adequate weight and base width.
Sheet-pile
structures should have sufficient pile penetration and tie-back anchor
capacity.
In order to decrease bank steepness and corresponding earth
pressures, the bank could be graded or the structure moved seaward. To
determine earth pressures on bulkheads, refer to EM 1110-2-2502,"Engineering
and Design of Retaining Walls" (currently being revised by Tulsa District,
Corps of Engineers).
Such scour
3 . A bulkhead should resist the effects of wave-induced scour.
may result in decreased pile penetration or Undermining of cribs. Sheet-
piles can be driven deeper than required in the absence of scour; sheet-
pile cutoff walls can be added at the toes of cribs, and armored toe scour
aprons can be used with any type of structure.
4 . Although rainwater will run off onto the backfill, overtopping in-
creased by wave reflection may a l s o add water to the backfill behind the
bulkhead.
This would increase the weight of the backfill and could in-
Measures to prevent or control overtopping are
crease the backfill scour.
discussed in CETN-III-8 (Seawalls).
5.
Steps need to be taken to eliminate the removal of backfill by ground
water flowing through a bulkhead, and the loss of toe soil by water
Drains in the bank or backfill and means to
flowing under the structure.
control overtopping will reduce the volume of ground water at the back of
Previous Page
