Pole foundation without concrete

[rubenpezu]

Hello,

I have to prepare the calculation of foundation of a pole but without use concrete. Only embebed in the ground. Usually we calculate this kind of foundation with Sulzberger method. But I am not sure how to calculate without concrete.

It is right if in my spreadsheet of Sulzberger change the weigth (kg/m3) of concrete, to calculate the foundation, to the weigth of ground? I am not sure about if this way is correct.
How I should calculate the foundation?
Have to be painted the part of the pole embebed in the ground? The pole will be galvanized.

Thank you for the help.

 

[VoyageofDiscovery]

My knowledge of steel poles directly embedded in ground, even galvanized, is they corrode away as the galvanizing just disappears. Ground resistivity, corrosive environment factors, etc and rate of loss of galvanizing must be calculated.

VoD

 

[rubenpezu]

Dear VoyageofDiscovery,

Thank you for your replay. Your are right and I am completely agree with you. Because what you said the part embedded will be paint to protect the pole. My problem is how to calculte the length to be embedded o the compression of the ground. How to be sure that the foundation without concrete is right. I have never had this kind of foundation.

Thanks.

 

[transmissiontowers]

The backfill that you use should be a little stronger than the soil that was removed. We typically use crushed rock. If you have PLS-CADD, there is a CAISSON module that will work. I am not a foundation guy but I have heard that it is a useable software but you need to know some soil mechanics to do it correctly.

_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[rubenpezu]

Thank you very much for your help.

 

[oldrunner]

Use the pole formulas in the IBC foundation section. Have your geotech give you a allowable passive pressure value and where the passive pressure starts. If the pole is only for vertical loads, then have the geotech give you a allowable bearing pressure and mayby friction against the sides of the pole.

This is pretty much old style engineering that has been around many years and if you are a civil/structural engineer should have gotten this stuff in school.

 

[msquared48]

Nothing saying that you can't add cement to the backfill mix to give it better cohesion with time.

Mike McCann
MMC Engineering

 

[rubenpezu]

Thank you all for your answers,

our costumer can't use concrete because the area where they have to install the pole es very inaccesible.

 

[msquared48]

rubenpizu:

In case you misunderstood, I said "cement", not concrete. There is a difference. The cement is the powder portion of a concrete mix, comes in 90# sacks and is easily transportable. Although not as good structurally as concrete, the inclusion of cement powder into the soil backfill matrix will stiffen the mix with time.

Mike McCann
MMC Engineering

 

[rubenpezu]

It right msquared48,

I have misundestand due to language. We assume that our client has taken this into account. According their instructions they want to fill the gap with the same soil. I have said them that they shoul have to compress the soil.

 

[stevenal]

Have you considered using a bog shoe? Won't help for uplift, but I don't see you state which direction the forces tend.

 

[rubenpezu]

What bog shoe means? Is the something similar than a grillage? Could you show me a picture or something?

Thanks.

 

[stevenal]

Here's one on a wood pole: Is this what you call grillage? I think the word fits.

 

[rubenpezu]

Thank you Stevenal.

Yes, more or less is what we call grillage. It is a kind of adaptation similar a grillage in transmission steel towers.

 

[leo5cn]

corrosion is more than anything else. you need to make the pole footing a cathode. Also soil horizontal spring contant to control ground line deflection.