Pressure of dirt?

Question

What is the amount of pressure per square ft. per depth that dirt applies to say an underground tunnel. Example- if i build a tunnel that is five feet under ground, what would be the pressure exerted by dirt, say under the heaviest conditions ex- wet, rocky soil.

Answer 1

For the conditions you describe you should consider the soil a viscous fluid.
Thus 'pressure`, (the strength of your shoring), would be density x depth.
Note: A heavy rain could easily render your soil both heavier and more fluid than your initial measurement.
Tunnels are NOT for amateurs.

Answer 2

cannot answer the question to be honest... i also have to know how big the tunnel is... how large its arc is, whether its an arc at all, if its not an arc what shape it is, the surface area of the ceiling, the height of the tunnel (because i would need to know the pressure on the other parts of the ceiling which, unless it its a rectangle, which would be a very poor engineering choice, would be unequal. i would also need to know the composition of the soil, what kind of rocks, the density of those rocks blah blah blah. i would also need to know if there were any trees or large plants above you that might stir the soil, or any worm or insect life in the dirt above.... the list goes on and on and on.......