PILE DRIVING 107 



PILE DRIVING 



Wooden Piles are generally of spruce, pine or oak. 

 Hemlock does not possess sufficient elasticity. If they are 

 to be used as columnar piles it is necessary that they be 

 absolutely straight ; if as bearing piles they should be fairly 

 straight ; and in either case of sound timber. The minimum 

 diameter of the butts is 12 inches and of the tips 8 inches. 

 Piles should be sharpened to a point before driving and 

 sometimes it is necessary to protect the point by an iron 

 shoe. The butts are cut off square and adzed so that a 

 wrought-iron band may be slipped on to protect the pile 

 in driving. Piles should be driven until the movement is 

 not more than one-half an inch under a 1500-pound ram 

 falling 15 feet on the last blow. 



Piles are used in park engineering in constructing founda- 

 tions for walls, abutments, spillways, etc. When used in 

 foundations it is better to cap them with concrete than to 

 attempt to construct a timber grillage. 



The land machine traveling on rollers is the common 

 type. Fig. 29, page 87, shows a land machine driving verti- 

 cal piles for the construction of a timber and earth bulkhead. 

 (See Figs. 35 and 36 on pages 109 and 113.) This machine 

 is held upright by guy ropes attached to " dead men " or 

 to posts set in the ground. These posts are sometimes 

 twisted into the ground where the soil is not very hard. 

 This method consists in attaching a long cross-piece to the 

 post by mepns of a chain. One or two men at each end of 

 the cross-pie co by walking in a circle and pressing downward 

 thus cause the post to sink into the ground. The ease, 

 simplicity and effectiveness of this method is astonishing 

 to those who have never witnessed it before. 



Concrete Piles are of two general types those that are 



