Short pile with tension and lateral load

[sdz]

I am looking at a short stiff pile with combined tension and lateral loading. Looking only at the soil strength my refences seem to suggest that there is no reduction in tension capacity due to lateral load, and vice versa.

I can accept this for a deep pile since uplift resistance will come mainly from the lower end while lateral resistance comes mainly from the upper section. But does this apply for a short stiff pile where the whole pile length is active in lateral load resistance?

The pile in question is 750mm (2'6") dia with 4m (13')embedment. L/D~=5.0

 

[Ron]

Lateral load reduces tension resistance on the passive side.

 

[rowingengineer]

Ron,
Seems back to front to me, or am I getting terms confused. My thoughts would be: the side where the lateral load is being applied would increase in capacity for tension and the side where the lateral load is putting the soil into active state would be reduced in tension capacity.


An expert is a man who has made all the mistakes which can be made in a very narrow field

 

[hokie66]

Yes, I agree with RE. The tensile resistance can be thought of as friction, so a lateral load will increase the friction on one side by the same amount as reduced on the other side. And I can't see how an uplift force would decrease the lateral resistance, so I think sdz's references are correct. Of course, when failure of one type occurs, the other type failure is soon to come.

 

[Ron]

Sorry guys...long day. "reduces" should have been "increases"

As hokie66 noted, the lateral pressure against the soil increases the friction component of the soil against the pile. Depending on the soil cohesion (or lack thereof) the actual friction on the active and passive sides can change substantially.

 

[asixth]

sdz,

Did you speak with the geotechnical engineer who is confirming the soil conditions for the pile to get their opinion on this issue?

 

[sdz]

asixth, No. I was checking some calcs and wanted to make sure the design assumptions were valid.