Sheet Pile Driveability

[aeoliantexan]

Are there guidelines or correlations for estimating the driving resistance of steel sheet piles? A proposed design calls for driving PZ-35 and PZ-27 sheets 75 feet. The top 35 feet is stiff to very stiff fat clay and medium dense sand, but the remainder is dense sand and hard fat clay.

 

[SlideRuleEra]

Steel H-pile should have roughly the same driving resistance as steel sheet pile. However, sheet pile are more susceptible to damage than H-pile because the sheet pile's interlock has to function.

I doubt if either PZ-27 or PZ-35 can be successfully driven to a depth of 75 feet in dense soil. Even if the piling / interlock can withstand the driving process (and that's a big "if"), it will be difficult to keep the embedded pile on line for 75 feet.

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[aeoliantexan]

Thank you. Are there guidelines for estimating the driving resistance of H-piles? Can this be done with a wave equation? Are there approximate correlations with SPT or unconfined strength?

 

[SlideRuleEra]

Driving resistance can be correlated to soil borings, etc. but to get a meaningful comparison you need actual field results of pile driving. Of course, pile driving data for similar type piling would be preferred. Since steel sheet piling is a type of friction pile, having data for concrete (displacement) pile would be on limited value.

The first (inexpensive) option would be to see if there are pile driving logs available for previous nearby projects.

The next approach (expensive) would be to a have a relatively small scale pile driving mobilization for simplified test piling. These piling are referred to a "index pile". Since most of the cost is the pile mobilization itself, it is typical to drive several index piles at various locations on the site. Make sure that the locations selected for the index pile will not cause problems during the actual project. A careful driving record is maintained. No load tests are performed. The index pile are usually extracted (if possible) for reuse. For best results, use the same type pile as will be used on the project (sheet pile, in your case). Be sure include simulated use of the interlock to see if it is damaged by driving. Use this data for project design.

A third (financially & schedule risky) way to address the issue is to design the project using best estimates of pile performance. Award the construction contract. The first work item is for the contractor to drive the index piles. Adjust the design based on this information... with the risk of substantial delays and contract cost changes.

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[FixedEarth]

The following linked paper has a good summary:

http://www.civil.ubc.ca/people/facu...g-Pile Drivability from CPT&WEAP Analysis.pdf

http://www.soilstructure.com/

 

[aeoliantexan]

Thank you SlideRuleEra and FixedEarth. Those are valuable suggestions.