Figure S. --Force 



components acting 

 on plane A-A ' . 



E 



Similarly, the tangential stress, x a , is equal in magnitude to the force T. From 

 equation 3, the equation for i a can be written as: 



T a = Y t z w sin6cos6 + Ysat (Z-ZJ sinGcosG. (5) 



Because the analysis will be on the basis of effective stresses, it is necessary to 

 determine the neutral stress, u. The neutral stress is found by use of a flow net, as 

 shown in figure 5. The pressure head along an equipotential line is equal to 

 (Z-Z w )cos 2 6. The neutral stress on plane A-A' is the pressure head multiplied by the 

 unit weight of water (y w ) : 



u = Y (Z-Z )cos 2 G. (6) 



Figure 4. — 

 Stresses acting 

 on plane A-A ' . 



B 



5 



