Parallel Retaining Walls

[bbookz]

A co-worker came across this perplexing condition. He recieved prototype drawings from an architect showing a building with a full basement 14'-0" below grade. The drawings show an exterior counterfort retaining about 3'-0" away from the buildings basement wall. The space between the walls is filled with gravel. The intended purpose of the exterior retaining wall is to relieve earth pressures against the basement wall so that this wall can be built out of CMU. Is this logical? I have always understood that the lateral earth pressure is a function of Ka/Kp, density, and depth. Does having only a 3'-0" width of soil behind the basement wall effect the pressure on this wall.

 

[csd72]

lkjh345,

I agree this may be an appropriate solution in certain circumstances, but I dont think this is one of them.

Why cant the basement block wall be designed as cantilevered?

csd

 

[concretemasonry]

bbookz -

Since these were prototype drawings, I suspect this was an architects idea of how to solve a soils/structural design challenge.

All that is laid out is the height of the walls and the requiremnt that the interior appearance of the wall be CMUs for some reason (possibly appearance compatibility with interior walls - a guess).

Ultimately, the best solution would meet these requirements for the site/soil conditions and the loads. Any structural design that meets the requirements and should be viable. If the cost is lower and the construction poses no problems, it would enhance the acceptibility.

Suggest an alternate since these are only "prototype" drawings and hopefully you can meet the requirements and provide a practical, economic alternate for the owner.

 

[bbookz]

Thank you all for your input. The links in the previous reply were especially helpful. I'm sure my co-worker will suggest doing away with the two wall system unless there is some arguemnt against having a single wall due to site conditions.