Multilayer Soil Model

[Power0020]

During analyzing soil resistivity values, the utility had the following criterion:

"For soils with resistivity value less than 500Ohm-meter, if the difference between the highest and the lowest readings are within 30 % then the soil can be considered as uniform soil. For soils with resistivity value greater than 500 Ohm-meter, if the difference between the highest and the lowest readings are within 20 % then the soil can be considered as uniform soil."

I couldn't locate any reference recommendation to that, any ideas?

 

[jghrist]

SES

http://www.sestech.com

has published many papers on grounding. Perhaps they or someone else has done a parametric analysis showing that a uniform soil analysis provides acceptable or conservative step- and touch-voltage values if the stated criteria are met. I haven't seen one.

 

[karls2]

Is it an additionnal request of your client ?
In most of the earthing ground calculation software you just have to fill table with your resistivity measures following depth and it automatically indicate if you are in one or several layers.

 

[Power0020]

@karls2 no it is not, it is just to know to what extent we can have accurate design with a uniform soil model.