Lateral pressure for rock cut plus soil backfill? 1

Draw a cross section showing the wall and the rock cut. Then draw a line rising from the toe of the wall at a 60-degree angle above horizontal. If the line misses the rock or cuts it only slightly, use conventional Coulomb active pressure. If the line hits the rock low down (a steep cut very close to the wall), then you can think about a reduction.

The exception to this is if you are planning to require tight compaction of the backfill against the wall with no deflection allowed, in which case it gets a lot more complicated because of stresses locked in by the compaction. Cross that bridge when you get to it, however.

There has been some good discussion in some other forums about this subject. Check these threads.

thread486-185817
thread274-166357
thread507-193368