Hello Kelly, thanks for sharing your expertise on this subject! I'm personally wondering about the use of earthbags when building a wofati/Oehler style house, using earthbags for the walls which are effectively retaining walls for the bermed soil. Normally there would be log posts with wooden plank/pole shoring, with a waterproofing barrier over that and then soil.
With earthbags replacing the shoring, and posts typically about 8-10 feet apart, are there calculations within the book or elsewhere which would suggest appropriate arcs to use? I would expect part of that answer depends on the pressure the soil is exerting, which would vary based on soil composition and moisture content, ie "it depends".
If I were to build a wofati/Oehler style house I would certainly replace the log posts with wooden plank/pole shoring technique with earthbags. They would likely last a lot longer than Oehler's method. You would still want to use a waterproofing layer between the cut berm and the bag wall.
The book does go into detail about how to design strong walls, either above or below ground. The shape of the wall makes a big difference, and in some cases buttresses, bond beams and internal pinning is advised.