Lateral Earth Pressure in a limited space 2

[Awre]

If I have a hollow concrete structure; 5 ft W X 10 ft L X 30 ft H that will be filled inside with soil, and nothing from outside "theoretically".

I need to calculate the earth pressure on all the sides, and wondering if the full lateral earth pressure will be developed within this limited space, or would it be less?

I think the pressure plane will not be developed due to the space limitation...

Would the lateral pressure equation: ϒhk_o on all sides remain correct, or can be reduced because of the limited space...

If it can be reduced, how can I calculate earth pressure?

Thanks

 

[EireChch]

What the hell are you building? A large flower pot?

Full pressure will definitely not be developed for the restrictions as you said. You also have a lot of wall friction on all sides which will greatly reduce pressure.

How conservative will you be if you just take full pressure?

Does this increase your wall thickness or rebar quantity by a lot? I am just trying to see if its worth working through a somewhat complicated issue.

Say you work out that the earth pressures are only 25% of full earth pressure. Calcs allow you to have a wall thickness of 150mm say, will you specify a minimum thickness regardless of what the calcs say.

To me it becomes a judgement of the difference between the "minimum wall thickness" and the "full pressure wall thickness"

 

[DaveAtkins]

I have often wondered about this myself. If the box were filled with water, you would have the full lateral pressure due to water. But soil is different. There is the wall friction effect, as mentioned by EireChch, but I also wonder if you cannot develop a full active failure wedge in such a small space. I think you will get a series of small failure wedges stacked on top of one another.

DaveAtkins

 

[BigH]

Check out silo design pressures

 

[Awre]

It is a hollow concrete modular block that will form a wall like what you see on highways, filled with soil. I was thinking about the soil pressure from the inside, at least on the front face; presumably, the pressure on both sides and the back will be nulled since the soil is on both sides of the wall.

I agree with @DaveAtkins that the soil pressure, in that case, is different than the water pressure...

I looked at the "silo design pressure", which @BigH suggests. I could get about 15% of the full pressure, which is the pressure I like to see!!! But Is it the correct approach?

Also, the papers I found assume "circular" silos, I thought there may be a further reduction because of the circular shape (?). I could not find anything researching a rectangular container. Could we have different forces/pressures if the silo is rectangular? or would it be the same as the circular?

Thanks everyone for any help...

 

[Settingsun]

Here's a published design simplification.

 

[mar2805]

This is egactly whats been bothering me also last few days.
I have a situation where we have a cut in rock, wich has an vertical face, and holds its self.
The investor wants to make an concrete wall infront of the rock face and decorate it with some king of stone.
I have to put make an retaining wall and backfill the space behind the wall with gravel/sand.
So my question would also be the same.
Depending on the WIDTH of the space behind the wall, are the lateral earth pressures the same for case A and case B?
See picture attached. Measures are in centimeers

 

[mar2805]

I found this article, but seems that for B/H=0,5 (close to my case) the reduction is not that much :-(
Only around 20% maybe.

 

[CarlB]

You might consider backfilling with geofoam, or CLSM. Also, tie-backs to the rock face.
Similar ideas are discussed at thread507-498616