The clay rich soils of Mid-Missouri expand and contract with moisture content. Clay expands when it becomes saturated with water from heavy rains, melting snow or water leaks, resulting in reduced strength. This loss of strength allows slabs to sink.
Concrete near trees or shrubs are prone to settle due to the loss of moisture in the soil as a result of the excessive amount of water the roots consume.
Many homes are built on backfilled areas. If the backfilled soil is not compacted properly prior to building, the area will slowly and unevenly compact over time resulting in concrete settling.
Improper drainage can result in saturated soil allowing concrete to settle. Something as simple as a misplaced down spout can result in serious consequences.