Our slabs on average are over 12 inches thick, weaved with rebar and in areas that were once crop fields, they do a deep water penetration watering to settle the soils.
Most new slabs or homes have what is called cable loc. its actually heavy one inch thick cables criss crossed throughout the slab. One end has a wide saucer on the end that is concave to the slab. its an anchor if you will. Then the end of that cable a threaded dowel and washers and a large nut or bolt. This is tightened up to pull everything together and keep it from having one end falling off or down.
The foundation watering really helps during the summer months. Most all homes have that black weeping soaker hose tent staked down around the perimeter of the home about 16 inches away from the slab and watering in equal increments all the way around the home.
If you think about it, where Texas is now located, this used to be the ocean bed, we have many basins around that were actually great salt lake beds like the Permian Basin in west Texas that you can find all sorts of ocean animal parts. So, the clay is our culprit. Unlike Missouri and northward, we don't have any rock in our soils except that shale and brittle white rock.