Geo Strata-gist
Geotechnical
Background: I am working on a project that proposes a new retaining wall near an existing wall (existing wall is the property line wall). The max retained height of the existing wall is around 6 ft. Generally granular backfill and foundational soils. The Architect would like to make the new wall as short and as close to the existing wall as possible without surcharging the existing wall. The structural proposed offsetting the new wall based on a 1:1 line starting from the bottom of footing (existing wall) to the bottom of footing (new wall) [see the sketch he provided below]
The structural informed me that the design was failing in sliding without passive resistance. He wants to know what percentage of the passive pressure he can apply to the key and footing of the wall. I figure the wall would basically need to be embedded below the intercept between the active and passive wedges [see schematic below].
Question 1: How would you guys go about this problem? I understand that passive pressures will generally dissipate in an infinite idealized soil profile (typically at around 2-2.5 times the embedment depth at the from the wall (similar to experimental findings Link); however, I am unsure how they would translate into lateral surcharge pressures on the existing wall. Any resources on that?
Question 2: If the existing wall has a decent amount of toe embedment at the face (more than needed to resist the existing retained fill in its original state), can the new wall be placed in the active wedge of the old wall and rely on the available (non-mobilized) passive pressures at the front of the existing wall? (Assuming the wall can resist the surcharge from a structural perspective). Hopefully that makes sense.
Thank you!
The structural informed me that the design was failing in sliding without passive resistance. He wants to know what percentage of the passive pressure he can apply to the key and footing of the wall. I figure the wall would basically need to be embedded below the intercept between the active and passive wedges [see schematic below].
Question 1: How would you guys go about this problem? I understand that passive pressures will generally dissipate in an infinite idealized soil profile (typically at around 2-2.5 times the embedment depth at the from the wall (similar to experimental findings Link); however, I am unsure how they would translate into lateral surcharge pressures on the existing wall. Any resources on that?
Question 2: If the existing wall has a decent amount of toe embedment at the face (more than needed to resist the existing retained fill in its original state), can the new wall be placed in the active wedge of the old wall and rely on the available (non-mobilized) passive pressures at the front of the existing wall? (Assuming the wall can resist the surcharge from a structural perspective). Hopefully that makes sense.
Thank you!
