Custom Search
|
|
|
||
 which are excavated shall be performed in addition to normal ground line preservative treat-
ment. All holes shall be sealed with preservative-treated wooden dowels or equivalent. Distinc-
tive durable, weatherproof tags shall be affixed to fumigant treated poles.
7.1.4.3 Reinforcement or Stubbing. Reinforcing or stubbing a pole is usually
done when the ground line area of the pole has been destroyed to the point where it is no longer
safe, but the upper portion can still support existing or expected maximum loads. Poles which re-
quire considerable transfer work are often stubbed. Wood stubs have been used in the past but
metal stubs (Figure 7-7) are currently specified in NAVFAC TS-20312. The reinforcement system
must also comply with the National Electric Safety Code. The pole must also be treated to ensure
that any active decay is stopped.
7.2 PILES. A pile is "a timber, usually round, that is embedded wholly or partly in surface soil or
under water soil as a support for a superstructure such as a bridge, building, trestle, wharf, etc."
Three types of piles are used. Foundation piles are entirely embedded in the ground and are capped
with masonry. They are generally used to support a structure in unstable soil. General piles are
used in fresh water or in soil and are partly embedded or are not capped with concrete. Marine piles
are partially embedded in bottom soil and partly exposed to salt sea water and are generally subject
to attack by marine organisms.
Those portions of piles exposed above ground line to the atmosphere or fresh water are subject to
the same problems as poles and much of the discussion on poles is applicable. However, pilings are
subject to additional problems.
7.2.1 Problems To Be Found.
7.2.1.1 Decay. After a pile is driven, the tops are usually cut off. This practice
exposes the untreated wood in the core to decay (Figure 7-8). Sometimes the cut is made at a steep
angle which exposes more surface area and further increases the decay potential.
7.2.1.2 Marine Borers. When pilings are installed in salt or brackish water, they
are often subjected to marine borer attack. Limnoria often attack piling at the intertidal zone,
whereas, shipworms attack it below the tidal zone.
7.2.2 Inspection Procedures. NAVFAC manuals MO-104, Maintenance of
Waterfront Facilities, and MO-104.2, Specialized Underwater Waterfront Facilities Inspec-
tion, provide excellent technical guidance for maintaining a good inspection and repair program.
The inspection procedures for decay as discussed under poles apply to piling. However, care must
be exercised if the wood is kept excessively wet, due to contact with water or where salt has been ab-
sorbed. The presence of salt will affect the readings obtained from the shigometer, electric moisture
meter or other devices which depend on the electric characteristics of wood.
7-15
|
 
|
|
|
||
