309. General Design . - The type wall chosen is the so-called dia- 

 phragm type illustr-nted in Figure 102. The dashed lines indicate the 

 dimensions of an equivalent rectangular cell used for stability calcula- 

 tions. The width (b) of the equivalent rectangle is the average 

 width of the actual cell, the length (L) is the length of one cell section; 

 and the distance (r) is the radius of the outside walls. Note that the 

 crosswalls have a slight arc for stability against differential earth 

 pressures due to partial filling of one cell before filling of the ad- 

 jacent cell is started. 



center line 



FIGURE 102 - Diaphragm type cell wall 



310. Failure criteria for such walls, if the piling has a 

 significant amount of penetration, are difficult to determine. However 

 there will be an adeuuate factor of safety if they ?re considered to be 

 open ended boxes resting on the bottom. In the example chosen, the rock 

 stratum is only two feet below the lake bottom and the open ended box 

 calculations will be fairly accurate. 



311. Piling Calculations . - Pile interlock tension resistance to 

 cell rupture is directly proportional to the cell fill pressure and the 

 radius of the cell wall. Expressing the fill pressure p in pounds per 

 square foot and the radius in feet, the interlock tension in pounds per 

 linear inch is given by 



t =iJi- (80 ; 



12 



152 



