Retaining Wall

[Calif]

How do you determine a how much of a heel you need for a concrete retaining wall with no toe. The wall holds up about 15.75 feet of soil on the toe side and 3 feet of soil on the heel side.

Sincerely,

Calif

The resisant virtues of the structure that we seek depend on their form; it is through their form that they are stable, not because of an awkward accumulation of material. There is nothing more noble and elegant from an intellectual viewpoint than this: to resist through form. Eladio Dieste

 

[oldrunner]

Hire a structural engineer or a civil engineer who does structural design.

 

[Calif]

I am a young engineer trying to figure out how to design a cantilever retaining wall with no toe. All the examples that I do have, have retaining walls with toes. The piticular problem I am having is finding the bearing pressure on the soil. I dont have any design examples to use.

Sincerely,

Calif

The resisant virtues of the structure that we seek depend on their form; it is through their form that they are stable, not because of an awkward accumulation of material. There is nothing more noble and elegant from an intellectual viewpoint than this: to resist through form. Eladio Dieste

 

[UcfSE]

If you don't have an example then you'll just have to do without. You can follow the examples you do have and modify them as needed. That's part of being an engineer, learning to think and apply your knowledge. You won't always have an example to plug-in answers.

 

[BigH]

Think of your 'toeless" retwall as a gravity structure where instead of concrete above the heel, it is the soil. The structure will need to have a fairly long heel. For MSE walls which is similar, you would have the "heel" be in the order of 0.7x the height - but this is for the strip too, so, 0.5x the height might be a good place to start. You will 'extend' the heel far enough back to minimize the front edge bearing pressure.

You can always, too, "reinforce" the front of the wall by putting the wall on a piled foundation;

you can take overturning moments (which is causing the higher "front face" pressures) by using ground anchors or dead-man anchors.

Also, there is some published data that suggest that the real 'front face' pressure (toe pressure) is not as high as theory indicates - sorry, can't remember the source off-hand but it was for some State DOT, I believe.

UcfSE has hit the nail on the head for so many engineers! Good one!

 

[oldrunner]

Sketch a free body diagram of the wall and estimate the heel length and depth.

1. Do your overturning moment analysis.
2. Do your resisting momentanalysis.
3. Check your factor of safety.
4. Sketch your bearing pressure diagram.
5. Determine if the bearing pressure is acceptable, depending upon your geotechnical consultants recommendation.
6. Check your total active force.
7. Determine whether there's enough material in front of the wall. The passive pressure and where it starts is also from your geotechnical consultant.
8. If you don't have enough resisting pressure, then add a key, varying the depth until you have enough sliding resistance with a factor of safety.

If you do this all on a spreadsheet and you document the spreadsheet carefully, you'll have a little routine to play what if with and to use later.

The bearing pressure is P/A +/- M/S if the bearing pressure is over the whole length of the bottom of the footing. If you have "tension", then use the method for determining the maximum pressure on a triangular section that doesn't have the whole length of the footing under pressure.

Chapter 12 of Schaum's Concrete book has very good examples that you can look at.

 

[PEinc]

Calif,

Use an example with a toe but make the toe about 0.01 feet long.