The use of effective unit weight

[echelon101]

thought I would post this here as it's a theoretical discussion.

I have doing some design and whenever the water table is above a soil strata you have to calculate the effective unit weight. (gamma'=gamma-gamma_w). I appreciate that this well established, but does anyone know it's origins? Or have done comparisons when it was not used in design.

 

[oldestguy]

I suspect Karl Terzaghi as the first to use it. I used to have his early book in the German language, but gave it away.

 

[fattdad]

the theory of effective stress is attributed to Karl Terzaghi.

f-d

¡papá gordo ain’t no madre flaca!

 

[BigInch]

"Comparisons when it was not used in design"

When you don't use it, pipelines, swimming pools, cooling tower basins, basements and other sometimes positively buoyant structures are much more likely to raise up from the ground. Stair towers, refinery column foundations and other wind loaded structures where resistance to uplift is required for stability at all times are far more likely to topple over. It's best to use it when necessary and be conservative as well, as consequences of not can be quite dramatic.

Independent events are seldomly independent.

 

[fattdad]

it is the principal of effective stress that helps us calculate the settlement response to dewatering also.

f-d

¡papá gordo ain’t no madre flaca!