Weather naturally moves through wet and dry cycles as the seasons change. While it’s normal for soil to be wetter and then drier and then repeat the process, it causes many issues for any concrete that’s resting above it. When the soil is saturated with water, either after heavy rain or snowmelt, the soil expands in size. And when the climate is dry, the soil shrinks.
This process of expanding and contracting leads to high amounts of pressure being exerted on the concrete above. This results in the concrete sinking and becoming uneven, and in worst cases, cracking or breaking off entirely.