P ^ safe bearing load^ pounds 



W s hammer weighty pounds 



Wp 2! pile weight., pounds 



h ^ free fall cf hahimer,, feet 



a fs effective area o" piston^ inches 



p -s-, mean effective stream pressure^ pounds per square inch 



s s! penetration of "inKing^, inches 



(taken as average of last 5 to 10 blows for a drop hammer 

 and as average cf last 20 blows for a steam hamraer). 



291. These formulas will give safe loadings of individual piles 

 provided the individual piles of a group are not so closely spaced that 

 skin friction is materially reduced. -2«- 



2?--', Internal Stress es. - Overturning Seaward . - On obtaining the 

 resultants of vertical and horizontal forces it is found that this 

 resultant would fall within the middle third of the base. The total 

 vertical force would be 20j060 pounds per foot downward and would be 

 applied 3.75 feet from B, The total horizontal thrust which would be 

 13s950 pounds per foot directed seaward^ would be applied 7.89 feet above 

 the base. From Figure 98.C, the resultant of these forces woiold fall 8,29 

 feet from B within the base_, or well within the middle third. Therefore., 

 there would be no tension in the base due to the force of the saturated 

 fill. 



293« Foundat ion Pressures. - Overturning Seaward. = 



Using f s ^ + ~ (see equation 69) 



where P,^ - 20^060 



A s 20 



M - 13,950 X 7.8U - 20,060 (13.75 - 10) « 32,000 



2 « 202/6 



■p ^^2^9. ■ 32^000 X 6 



■^ ^ 20' - "~uoo 



= 1003 + ii.80 

 The preswsure distribution xTOuld be as shown in Figure 99 by the line CD, 



* See C. Terzaghi^ Trans. ASCE^ Vol. 93, p. 290, 



