i've tried to modify your new script (the one with the sheet wall) this way (last lines only):
// excavate the first stage from top and solve to equilibrium
excavate("region",2.5,-1.5)
solve()
plot("contour","xdisp")
plot("struc","beam","moment")
// excavate the second stage from top and solve to equilibrium
excavate("region",2.5,-5.0)
solve()
plot("contour","xdisp")
plot("struc","beam","moment")
// excavate the last stage from top and solve to equilibrium
excavate("region",2.5,-8.0)
solve()
// plot x-displacement contour
// and plot moment force in the same plot
plot("contour","xdisp")
plot("struc","beam","moment")
i've done this to see what happens at every stage. adonis correctly produces 3 images but in every image is always displayed the contour map of the last stage. instead, the moment along the wall is the one acting at that stage.
i think that this happens because the space memory for the contour maps is always the same, so the new one overwrite the previous. why don't you introduce an option (set to 1 by default) to let the user define how many contour maps he wants?
to not waste memory, that number could be internally set again to default at each new model, just like gravity.