Steel Piles bearing on Rock with Open Pointed Tips

[PT999]

I am reviewing pile logs for 8 5/8" diam / 0.322 wall thickness helical steel piles driven with open ended pointed tips. Load will be 40 tons

Piles are spinning out on rock. So torque reading on pressure gage connected to the torque motor is zero. Is there a concern that the pointed tip may fail
(bend over) under load?

Is a solution to clean out soil at tip and fill with grout which will ooze out at the tip?

Or should the piles be changed to flat (not pointed) open tips and then grout filled also to ooze out at the open end and provide bearing on the rock?

 

[PEinc]

If the helices are spinning and the shaft tip is on rock, the helices provide no capacity. You basically have a pipe(?) column bearing on rock. Capacity would depend on the strength of the pipe, the amount of pipe cross-section area bearing on rock, and the bearing capacity of the rock.

Grouting could help provide full and even bearing for the end of the pipe but the grout strength may be less than the rock strength.

You have a few options if the current condition does not figure. You could add more of the same piles. You could drill down through the pipes and socket a steel core to make a micropile, or you could possibly switch to drive piles.