Max. wall deflection

[Okiryu]

What could be the max. allowable deflection for the retaining wall shown in the attached? Is the allowable deflection for this condition indicated in the codes? To develop active pressures, I think that a movement of 0.001H can be considered (for granular backfill), so I was planning to use this as the max. allowable deflection. We need to check with the designer, but perhaps he considered at rest pressures to design that wall since the 2F slab restraint movements of the wall. But, I think that since the wall is constructed first and then backfilled, some deflection can be allowed.

BTW, the construction sequence will be:
1. Construct the retaining wall
2. Backfill
3. Construct the Slab on grade
4. Construct the 2F walls

So, concern is about the needed to brace the wall on the top to limit deflection. But if deflections are within the allowable deflection, bracing may not be required.

Do you see any other issues or do you think that the construction sequence can be improved?

Thanks !!

 

[dcarr82775]

There is no Code requirement I am aware of for the movement in the retaining wall you describe. All the components need to be able to accommodate the potential deflection, and the wall itself needs to account for the added eccentricity of gravity load from the building above resulting from the deflection.

 

[Okiryu]

dcarr82775, Do you think that is reasonable to consider that bracing may be required because the walls were designed based on at-rest pressures, so they were designed assuming zero deflection of the wall?

 

[Okiryu]

Other option is to backfill (at the same time) both sides of the wall to balance/avoid excessive wall top deflections. Then remove the soil at the road side after the building slab is completed.

If there is an allowable maximum deflection, then we will not need to backfill for the entire height of the wall at the road side (assuming that we are using the same type of soil in both sides).

My doubt is about what type of pressures do I need to consider in both sides of the wall.
I think that the correct way should be to consider active pressure at the buidling side (left side of the wall, since we will backfill up to the entire height of the wall) and passive at the road side (assuming that there is some allowable deflection, so we will have only a partial backfilling, since we will not backfill the entire height of the wall).

My first approach was to consider active in both sides, which it may not be correct.

Do you think that this can be a viable/correct option?