I have run into an unpleasant surprise when I started repairing the collapsed foundation wall at the house I am working on, and I'm hoping that someone here may have some advice about what to do now. The wall I am working on is about 12 feet long and 6 feet high, and close to 2 feet thick. In the middle near the bottom of the wall there is a huge stone which has a pretty smooth top set at a slope of about 30 degrees. I dug under the stone and around it and tried to roll it forward so the sloping face would become vertical, but it would not move with a 4-1/2 foot crowbar or an 8 ton jack. I am thinking about several possible ways to repair this wall, but they may all be bad ideas for all I know.
1. Make a buttress of stone in front of the sloping stone
2. Drill into the stone (with a hammer drill?) and put some pins in, sticking up.
3. Lay some rebar across the stone, with the ends buried in the new wall on either side
4. Make a header over the sloping stone with some heavy steel, supported on either side on the new wall.
I'll be grateful for any ideas or guidance. I had thought it would just be a matter of removing the rubble from the collapse and cleaning up and re-laying the stone, but I wasn't expecting this extra wrinkle.