PILES AND PILE DRIVING. 279 



Shakes. Shakes are splits or checks in timber which usually cause a separation of the 



\\ci<nl Ixiw.i n annual rings. 



Ring Shake. An o|x-ning between annual rings. 



Through Shakes. A shake which extends Ix-tween two faces of a timber. 



Rot, Dote and Red Heart. Any form of decay which may be evident either as a dark red 

 discolorat i. m not found in the sound wood, or by the presence of white or red rotten spots, shall be 

 omMcli ivd as a defect. 



Wane. (See definition under the subject of Structural Timber.) 



Note. See additional definitions of defects under Structural Timber. 



, PILES AND PILE DRIVING.* 



The following definitions and the principles of Pile Driving have been adopted by the Ameri- 

 can Railway Engineering Association. 



Pile. A member usually driven or jetted into the ground and deriving its support from the 

 underlying strata, and by the friction of the ground on its surface. The usual functions of a 

 pile are: (a) to carry a superimposed load; (b) to compact the surrounding ground; (c) to form a 

 wall to exclude water and soft material, or to resist the lateral pressure of adjacent ground. 



Head of Pile. The upper end of a pile. 



Foot of Pile. The lower end of a pile. 



Butt of Pile. The larger end of a pile. 



Tip of Pile. The smaller end of a pile. 



Bearing Pile. One used to carry a superimposed load. 



Screw Pile. One having a broad-bladed screw attached to its foot to provide a larger bearing 

 area. 



Disc Pile. One having a disc attached to its foot to provide a larger bearing area. 



Batter Pile. One driven at an inclination to resist forces which are not vertical. 



Sheet Pile. Piles driven in close contact in order to provide a tight wall, to prevent leakage 

 of water and soft materials, or driven to resist the lateral pressure of adjacent ground. 



Pile Driver. A machine for driving piles. 



Hammer. A weight used to deliver blows to a pile to secure its penetration. 



Drop Hammer. One which is raised by means of a rope and then allowed to drop. 



Steam Hammer. One which is automatically raised and dropped a comparatively short 

 distance by the action of a steam cylinder and piston supported in a frame which follows the pile. 



Leads. The upright parallel members of a pile driver which support the sheaves used to 

 hoist the hammer and piles, and which guide the hammer in its movement. 



Cap. A block used to protect the head of a pile and to hold it in the leads during driving. 



Ring. A metal hoop used to bind the head of a pile during driving. 



Shoe. A metal protection for the point or foot of a pile. 



. Follower. A member interposed between the hammer and a pile to transmit blows to the 

 latter when below the foot of the leads. 



PILE-DRIVING Principles of Practice. (i) A thorough exploration of the soil by borings, 

 or preliminary test piles, is the most important prerequisite to the design and construction of 

 pile foundations. 



(2) The cost of exploration is frequently less than that otherwise required merely to revise 

 the plans of the structure involved, without considering the unnecessary cost of the structures 

 due to lack of information. 



(3) Where adequate exploration is omitted, it may result in the entire loss of the structure, 

 or in greatly increased cost. 



(4) The proper diameter and length of pile, and the method of driving depend upon the result 

 of the previous exploration and the purpose for which they are intended. 



(5) Where the soil consists wholly or chiefly of sand, the conditions are most favorable to 

 the use of the water jet. 



(6) In harder soils containing gravel the use of the jet may be advantageous, provided 

 sufficient volume and pressure be provided. 



(7) In clay it may be economical to bore several holes in the soil with the aid of the jet before 

 driving the pile, thus securing the accurate location of the pile, and its lubrication while being 

 driven. 



(8) In general, the water jet should not be attached to the pile, but handled separately. 



(9) Two jets will often succeed where one fails; in special cases a third jet extending a part 

 of the depth aids materially in keeping loose the material around the pile. 



(10) Where the material is of such a porous character that the water from the jets may be 



* For an elaborate bibliography on " Piles and Pile Driving" see Am. Ry. Eng. Assoc., Vol. 10. 



