Rule of thumb for Estimating Sheet Pile Length for Cantilevered and Anchored Sheet Pile Lenghts 1

[CWEngineer]

I am trying to figure out if there is a rule of thumb for estimating the length of a sheet pile that is cantilevered and anchored. Also, is there a particular reference that this discusses this.

Thanks

 

[Guest262653]

My initial guesses for embedment depths are around the following numbers:
Cantilevered: 2 * Retained Height (i.e. length = 3 * retained height)
Anchored: 1* Retained Height (i.e length = 2 * retained height)

Hope it helps.

 

[BridgeEI]

The rule for cantilevered sheet piling I use is 1/3 above and 2/3 below. I don't know of a rule for anchored, I think it's more dependent on the location you anchor which could depend on a variety of factors. I'm sure someone has a much better answer for you.

Avscorreia beat me to it.

 

[SlideRuleEra]

From a historical viewpoint, by the 1930's steel sheet pile had been in use for several decades. Therefore, there was significant experience with what worked and what did not. At that time, Carnegie-Illinois Steel (a predecessor to US Steel) published "experienced" based guidelines that can be summarized as follows:

Cantilevered: "Penetration below the bottom should equal approximately the unsupported height above."

Anchored: Penetration below the bottom should equal between 20% to 75% of the distance from the tie rod to the bottom. Percentage determined by judgment of soil conditions and depth of channel (for waterfront structures).

You can read the exact wording and proper context from the 24th page of "US Steel Sheet Piling Design Extracts", located on my website:

http://www.slideruleera.net/Steel-Piling.html

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[Ron]

SRE...making us all look like amateurs again!!....but much appreciated! U da man!

 

[SlideRuleEra]

Thanks, Ron. I'm just glad a few questions come up where an answer can be found in the past.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[Guest262653]

Thanks for the info, SRE. My guess for cantilever walls is for a safety factor of 2.0 on Rankine passive pressures and using the simplified fixed earth support method. For lower safety factors and different earth pressure coefficient calculation methods, these embedment depths fall quite drastically.

I've created a simple spreadsheet for the calculation of penetration depths for cantilever walls and did a quick parametric study, varying friction angle and getting D/H ratios. If someone is interested, it can be found at the following link:

https://www.dropbox.com/s/fyj2ue8jfmqysct/CantRetWall_v1.0.xlsm?dl=0

 

[CWEngineer]

Thank you, really appreciate your help. Do you guys know if there is a similar rule of thumb for shoring (soldier piles - H-piles with wood lagging)? Thanks