Broms Lateral Pile Analysis

[craigmcg]

In analyzing "long" free-headed laterally loaded piles in sand using Brom's analysis, I'm finding that the allowable loading based on pile bending capacity decreases with an increase in the soil friction angle. I'm not a geotechnical engineer but this seems to defy general logic to me. If the friction angle was decreased, wouldn't the point of fixity theoretically increase in depth? From this, a longer moment arm would then lead to a decrease in the allowable loading.

I can't find any errors in my calculations and am having a hard time wrapping my head around this.

Anybody's input is welcome.

Thanks.

 

[jdonville]

craigmc,

Don't forget to base your allowable load on your deflection criteria. Typically, a large deflection (inches) is needed to actually mobilize the lateral capacity.

Second, I haven't checked, but doesn't Brohm's method require you to look at "short" capacity, too, in order to determine whether "short" or "long" is appropriate?

I will try to refresh myself on Brohm's and get back to you, unless someone else has it closer to mind.

Jeff

 

[Panars]

Using Brom's method for long piles in cohesionless soil, you should see an increase in the ultimate lateral resistance with increasing friction angle of the soil, assuming all other parameters are constant.