Poisson's ratio as well as undrained shear strength. Also, it should be noted 

 that in the sample problem of Reference 6, a Poisson's ratio of 0.4 was assumed 

 for the soil. A value of 0.5 would have been more appropriate for undrained, 

 short-term breakout so a significant portion of the difference between the two 

 predictions may be attributable to the Poisson's ratio assumption rather than 

 to any basic analytic discrepancies. 



Considering the complexity of the breakout problem, particularly 

 with regard to time effects, there is little justification for undue sophistication 

 in formulating the initial limiting equilibrium relations. Modifications will have 

 to be made to any relationship to account for actual field effects. It is much 

 simpler to modify a relationship such as Equation B-3 than it is to modify an 

 involved numerical analysis. 



42 



