Case III. Plane A- A ' below the water table with, the water table below the ground 

 surface. For this general case, shown in figure 8, the tangent of the obliquity angle, 

 4>, is the quotient of the tangential stress and the effective normal stress: 



Y Z smGcose + y ^ (Z-Z )sin8cos6 

 t w sat vr 



tan <|j = • 



yZ cos 2 e + yAl-Z )cos 2 9 



t W D W 



Rewriting equation 11 and solving for the obliquity angle yields: 



(12) 



B 



Figure 8. --Stress relationships for plane A-A ' below the water table 

 with the water table below the ground surface. 



8 



