HORIZONTAL 



= 35^ 



i 



Figure 11. — Distribution of active and passive stresses on planes normal to ground 

 slope under assumptions of the infinite slope theory (Q = 25° j cf) = 10°j o = 500 

 p.s.f., = 220 p.o.f., > 11.85 ft.). 



It will be recalled from equation 10 that, in the case of seepage, S is the 

 seepage force per unit area. However, it is convenient to consider S as simply an 

 incremental shear stress which may be expressed 



S = T - a tan 

 ns n 



(36) 



In cases without seepage, and under the assumptions of the infinite slope theory, 



T = tan 6, and therefore S = 0. 

 ns n 



Combining equations 35 and 36, 



= a (1 + 2 tan^ A") + 2 c tan i 

 s n 



{(a tan d) + c) ^ 



cos (j) ^ n ^ ^ 



T 2} 

 ns 



(37) 



where, again, the (+) and (-) signs are associated with the passive and active condi- 

 tions, respectively. 



24 



