_L = o = ^-16/ =0 12 ri321 



L L tane 14.56(0.667) ^'-^^ • ^^^^> 



Taking first the simple expression for the slope friction angle 

 (eq. 126) 



0.26 

 tan2(|) = 0.25 {—) F^ , (133) 



o 



in which F is obtained directly from Figure 17 



Fg = 0.83 , (134) 



since Fg is not a function of (j) for this low value of l^/L. For higher 

 values of ^^/L a value of F^ corresponding to an assumed value of <}> is 

 obtained from Figure 17 and substituted into the right-hand side of 

 equation (133) to obtain a new value of <(> . With this new value of (j) a 

 better estimate of Fg is obtained from Figure 17 and the procedure is 

 continued until convergence is achieved. 



In the present case equation (133) may be evaluated directly to 

 give 



0.26 



•1.167^ 



tan2(J> = 0.25 ( "'j^^ ) 0.83 = 0. 25 (0. 56) (0. 83) = 0.116 , (135) 



and the value of <^ is obtained 



^ = 6^= 3.3° . (136) 



With £g/L given by equation (132) and (f) = 3.3 , Figure 15 gives 

 the predicted value of the reflection coefficient 



R = 0.94 . (137) 



ps ^ 



The present calculation corresponds to a steep slope, tanSg = 1/1.5, 

 and as discussed in Section III. 4 the estimate given by equation (137) 

 should be corrected by the factor < R^/Rp> given in Table 2 corresponding 

 to <^ obtained from equation (126) and tanBg = 1/1.5. The estimate of the 

 reflection coefficient therefore becomes 



R = <R /R > 0.94 = 0.92(0.94) = 0.86 . (138) 



ps m p 



77 



