1200 ft. slip along an elevator built in 1929

[connect2]

We are currently looking at at an elevator built in 1929-30. Along one side of the elevator, 1200 foot long, is a slip built originally to unload ships via Marine towers ... way to complicated to explain here. Long story short we are currently considering adding 24,500 metric tonnes of storage along this slip in the form of 21' dia x 70 tall cold formed steel hopper bins. The slip and for that matter the whole elevator is founded on timber piles. Its about 10 to 15 feet of fill placed over about 40 feet of clay marl, then 15 feet of clayey silt transforming into 10 feet of silty clay ending up up as 5 feet of silty sand lastly about 3 feet of mixed sand glacial till finally bedrock.
Thoughts on how far they might have driven the piles in 1929?
The only info on the piles is they were supplied locally which likely would have meant white and red pine, hemlock perhaps, maybe even red oak? ....
No info on sequence, concerned about negative skin friction.
Perelim on analysis yields axial loads in the 25 ton per pile nieghbourhood, so is close, condition aside. Thoughts?

 

[SlideRuleEra]

Pile driving in 1929 was done essenitally the same way as today. Other than simple drop hammers, most piling were driven using steam power. Many hammers used today with compressed were likely built before 1929 for use with steam. The equipment available was more than adequate to drive any timber piling until the pile itself failed.

IMHO, load tests on existing piling would be wise.

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[connect2]

SlideRuleEra:
Just finishing the reports conclusions on new steel structure under the bins and their distribution to achieve pile loads not greater than 20 tons range and have include testing of the piles and consolidation and other geotechnical testing as 'shall' do items as the next phase.

 

[msquared48]

I would test drive a few of the existing pile to see if there is any movement. Might carry far more than you think after all these years. Definitely a geotech's call here.

I have run into 18" diameter DF pile driven at the turn of the century that put 12" diameter, 25 ton steel pipe pile to shame.

Mike McCann
MMC Engineering