undermining existing ACP pile cap??

[boffintech]

If the path of your new subway was blocked by existing auger-cast piles under 4 pile-caps holding up 1,000,000 pounds worth of structure and there was no other reasonable course for your train to take....you could place additional footings supported by micro-piles on each side of your pile-caps and then suspend the existing pile-caps on steel beams spanning between the new footings. Then you would only have to dig out the soil under your existing pile-caps and cut off the auger-cast piles. Simple.

http://i44.tinypic.com/ygis8.jpg

http://i40.tinypic.com/ip86zm.jpg

 

[BAretired]

Be sure to check your bending moments.

BA