Underground tank Stability against Buoyancy

[melsawaf]

dear specialist

i`m going to design an underground water tank using soil above toe in addition to the tank dead weight , the GWT level at the grade level ,
the question is :

could i use a cement sand soil instead of clay soil ?
what is the soil submerged weight ?
what is the inclination angle to be considered ?? 40 , or less ??

 

[oldestguy]

In order to be conservative, some factor of safety maybe is better than none, by using smaller end of unit weight and friction values.

So In answer: Yes: 60 #/cf : 20 degrees. This allows for possible construction work not being the best.