This section is from the book "A Treatise On Architecture And Building Construction Vol2: Masonry. Carpentry. Joinery", by The Colliery Engineer Co. Also available from Amazon: A Treatise On Architecture And Building Construction.
Cluster Piles With Brick Arches. Piles are sometimes driven in groups, and the building is carried on arches sprung from one group or cluster to another. Fig. 27 shows one form of this method of construction which has been successfully used on alluvial soil.
The piles shown at a are driven in groups of nine. They average 20 feet in length and are driven until they sink about 1 inch at the last blow of a hammer weighing- 1,200 pounds. On the piling, 3"Xl2" plank are laid transversely and longitudinally, spiked to the top of the piling, as shown at b, b. The stone skewbacks c are placed on this planking, and tied together with a l 3/4-inch tie-rod d, upset on one end and secured by a nut and washer on the other. The brick segmental arch e is then sprung between the skew-backs. This arch has a radius of 15 feet, and is laid up in four courses, or rowlocks, of brick. The brickwork is 24 inches thick up to the level of the water-table of the building.
Terms Used In Pile Driving. The technical terms used in pile driving are descriptive of the form or position of the piles, or the manner of their driving.
A screw pile has an auger at the lower end, and is sunk by a rotary motion, aided by downward pressure.
A close pile is one set close to another when the pile already driven shows signs of weakness.
A false pile, or follower, is an additional length added to a pile for deeper driving. Fig. 28 shows the manner of connecting the first pile driven and the follower; a is the first pile, b is the follower, and c is a dowel to preserve the alinement of the two piles. At d, d are shown wrought-iron straps, made usually of 2"X1/2"X20" iron, to bind the two piles together.
A gauge pile is a preliminary pile driven to mark the desired course.
A filling pile is one put in between gauge piles.
A guide pile is one driven to mark the limit of the field of operation.
A wale is a horizontal string piece to bind the piles together.
Pile hoops are bands around the tops to prevent splitting.
Test piles are the first piles driven to test the bottom, and should not be less than 6 inches in diameter.