a regional thing. I live in Texas and all we have is clay soils with speratic heavy rains but mostly droughts.
Tim, what one does to prepare and to keep the clay stable is to set those black soaker hoses all around the foundation about 16 inches from it. then stake them down with tent stakes. During the summer, fall and spring, you will want to water your foundation every 10 days or so unless you have sufficent rains. You need a "Y" gate attached to one water faucet for this purpose. Water one half the foundation one night and the other half the next night. NEVER water only one side, that will cause the other to fall and the watered to rise.
Clay is very very flexible and with water it will increase its density and push the house up, when bone dry it will condense and cause the foundation to fall.
When the soils begin to pull away from the side of the foundation you are not watering enough at all, keep watering until the soils come back to the foundation. This will be your barameter.
When we have our water rationing days in the summer, I will forget the grass and flowers and consentrate solely on my foundation and trees.