6 minute Solutions Request Assistance

[Ranger88]

On 6MS second edition,

#86:

Why do we ignore the passive pressure for determining the pivot point of a anchored flexible bulkhead? The passive pressure is large.. That does not seem sensible.. Can someone please clarify why? Thank you.

-Bruce

 

[geomane]

I can't really follow his methodology in this one. Are you using the fixed earth support method or the free earth support method? 

 

[P-E]

Six min solutions is a terrible book.   I burned mine. 

 

[Ranger88]

I can't really follow his methodology in this one. Are you using the fixed earth support method or the free earth support method? 

JMCC06,

From what I am following, they take a moment at the pivot point and ignore the passive pressure in front of the bulkhead; its is the free earth support method.  However- (this applies to this problem and sheetpile design in general) How do I know what method to design by for the PE?  I could have used the free earth support method as 6MS did, or I could have induced a large moment with the fixed earth support method...

Thoughts?

Thank you!

-Bruce

 

[geomane]

I figured you would have to use the fixed earth on this problem. This is because, per Das, Principles of Foundation Engineering, "The free earth support method involves a minimum penetration depth. Below the dredge line, no pivot point exists for the static system." He also states, "When using the fixed earth support method, we assume that the toe of the pile is restrained from rotating", as stated in the problem.