Stacking retaining walls

Question

Stacking retaining walls

hotmailbox (Structural)

(OP)

15 Sep 22 19:26

Please see the sketch below and discuss:
The wall #1 was designed for retaining height H1 and 1:1 slope backfill. All good. Now the client wants to build retaining wall #2. Technically we'll remove a decent soil mass behind the wall #1 to build the new wall and think there is no extra load or surcharge on the wall #1. Is this true? The city asks that the wall #1 shall be design for retaining height of H1 + H2 or the surcharge from wall #2. What do you think?

phamENG (Structural) · Answer 1 · 2022-09-15 19:32:27

RE: Stacking retaining walls

phamENG (Structural) 15 Sep 22 19:32

I think the city is correct.

Celt83 (Structural) · Answer 2 · 2022-09-15 19:36:11

The rear wall alters the stabilizing soil mass over the wall# 1 heel in my opinion.

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hotmailbox (Structural) · Answer 3 · 2022-09-15 19:41:19

Don't you think the slip surfaces for wall #2 would be inside the governing slip surface for wall #1?

geotechguy1 (Civil/Environmental) · Answer 4 · 2022-09-17 23:22:14

The city is right.

To design them 'independently' you'd want a separation distance of twice the height of the lower wall (and then you would still need a global stability check).

kieran1 (Structural) · Answer 5 · 2022-09-20 08:31:32

How do you intend to build this?

Kieran

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Stacking retaining walls