Tiered Retaining Wall with Geofabric

[AndBre44]

Looking for some guidance as someone who is in unfamiliar territory; I have a situation where a client is looking to install a tiered retaining wall in their residence backyard to replace a currently failing wall. They're looking to use a tiered wall design, and rather than poured concrete are looking to use something such as a Heritage masonry block utilizing Geotextile fabric for ease of installation (not a lot of access to the backyard). I know that for tiered walls the rough estimation is that you need twice the lower walls height in distance between the top of the lower tier and the bottom of the upper tier, but does the use of geotextile fabric change that consideration at all?

My thought/where the question comes up is, if I have a 4ft high lower wall (meaning 'typically' my next tier would be a minimum of 8ft behind this), but then I have a 6ft geotextile fabric length requirement on that lower tier; should I instead use double that geotextile fabric length and have the tiers at a 12ft length? Or is it a non-issue as long as the fabric is within the 8ft distance between tiers?

Any insight into this would be appreciated.

 

[swazimatt]

Not sure where you are based, but often the manufacturers of geotextiles/geogrids or block retaining walls offer a level of design, might be worth contacting them

 

[EireChch]

I have not heard of that rule of thumb for tiered walls. The issue with tiered walls is that you need to check global stability. The walls can work indpenedently of one another but may not work together globally.

Also re your terminology. Its a geogrid you are using, not a geotextile fabric. Geotextile fabrics are for drainage and separation etc they do not provide any real strength, especially in your scenario (pull out strength)