Working on or near a foundation
Things to consider:
- Soil Bearing Capacity
- Soil Liquefaction potential
- Angle of Repose
- Rule of thumb when digging near a foundation -- allowance for a digg free 45 degree cone that spreads outward from the bottom of the foundation footing. The actual pressure cone critical for support is only 60 degree, but 45 allows for leeway and is simpler to measure.
When replace foundation single story, wood frame homes allow for unsupported sections walls up to 15 feet while work is being done. Obviously, don't leave the wall unsupported permanently.
Excellent source of information: https://pro.homeadvisor.com/article.show.Footing-Fundamentals.13700.html