Thanks for the responses, they were helpful. I used a number of iterations on the design. Slope/W has a nice feature in the sensitivity analysis where you can see how varying the material properties will vary the FOS without having to run it too many times. Interestingly we got the highest FOS...
Does anyone have experience modeling stacked rock walls, (rockeries, or gravity walls) in SlopeW? I wonder whether to break up each layer as a separate unit. Any suggestions for phi and C for rockeries?
Thanks
AndyJG