parts of each batten lying beyond the timbers are hinged for raising. The template is lashed to the outer piles in the bent already driven by means of a pair of wire ropes, equipped with turnbuckles as shown. After the piles in the new bent are driven, the hinged parts of the battens are raised, the wire ropes are let go, and the template is floated out from between the bents.
Piles can be driven either tip or butt down; they may be driven butt first if a large bearing area is required or if the pile is to resist an upward force.
Lagging is used to increase the resistance of a friction pile. Before the pile is driven, long, narrow strips of wood or steel are lag-screwed to the pile, as shown in figure 8-22. These are attached to the lower part of the pile from approximately 12 inches above the tip to the limits of the depth that the pile is expected to penetrate. The extra surface area increases the load-carrying capacity of the pile but tends to make it more difficult to drive.
After the piles in a pile bent have been driven, the remaining steps in constructing the bent are ALIGNING, CUTTING, CAPPING, and BRACING the piles.
Piles in a bent are straightened with tackles and brought into alignment with an ALIGNING FRAME, as shown in figure 8-23. After the frame has been put on, a working platform, like the one shown in figure 8-21, is usually erected to support the personnel who will cut, cap, and brace the piles.
A timber pile selected for a bent should be long enough to leave 2 or 3 feet extending above the specified elevation of the bottom of the cap after the pile has been driven to the specified penetration. The piles are then cut to the specified elevation with a chain saw or a crosscut saw.
Because the cap must bear evenly on all the piles in the bent, it is important that they all be cut exactly the same elevation. Ensure this by the use of the CUT- TING GUIDE or the SAWING GUIDE, as shown in
Figure 8-22. - ;Lagging of a timber friction pile.Continue Reading