Civil engineer guide to fighting positions, shelters, obstacles

AFH 10-222 Volume 14 1 August 2008 119
5.9. Timber and Lumber Revetments. There is little difference between
timber and lumber revetments except the raw materials. They are both built
like plywood walls, except that the inside facing material is either saplings or
lumber (Figure 5.22). The facing timbers of the timber revetment are usually
2- to 3-inch sapling trunks laid parallel, one on top of the other and fitted together
to avoid gaps. The facing lumber of a lumber revetment is a minimum
2-inch thick board or 2 inches of layered plywood sheathing. For a timber
revetment, the posts are usually 6 inches in diameter and spaced no more than
2 feet apart, while lumber revetments use 2- by 4-inch studs spaced about 12
inches apart. The posts are normally set 2 feet into the ground for bracing and
have 3 tie-cables run between opposite posts. One cable provides a tie at midheight,
while the other two cables are at about 1/6 the height from the top and
the bottom, respectively. As a minimum, every other post is tied. The ends of
the revetments are blocked with additional posts of timber or lumber; therefore,
the minimum width of the revetment can be greater than the plywood
wall type revetment. As a minimum, the walls are built in cells every 10 feet.
A cross-braced wall is built within the lumber revetment by using 2 sets of 4-
by 4-inch posts set 2 inches apart to create a slot on the inside of each wall.
Then 2-inch thick lumber is stacked in the slot to create a cross-braced wall
section. For the timber wall, two sets of the 6-inch diameter posts are set
about 3 inches apart on each side of the wall. Cross members are notched and
stacked to fit into the facing logs. Timber and lumber revetments are filled
with soil to provide strength and stability for these expedient structures.
Figure 5.22. Timber and Lumber Revetments.