Retaining walls with 45° backslope
How would people approach this usually?
Timber pile retaining wall, cohesive soils (max retained height about 1.8m). Soils routinely manage a 90 degree cut (a lot of our historical roads have this batter all over the place, sidle fill construction) and only come undone during extreme storm events where the top layers (1m or so) lose suction.
Using slope stability software to get a design action for a modified broms (a la caltrans) style equation gives me a very high load that would require hefty steel sections.
WALLAP is fine until I go to do seismic checks and switch to wedge stability. Switching to wedge stability gives even my pre excavation stages metres of movement. Modelling backslope as a surcharge as per their guidance. Using a boussinesq method to derive a resultant force from the retained backslope causes the model to fail even before wedge stability is turned on.
I'm at a small regional design consultancy so I only have limited software available.