Your uneven driveway is caused by problematic soil. Soil washout, dry conditions, or expansive soils can all contribute to a sinking driveway. Clay soils are extremely common in Travis County and Bexar County. The dry environment of Texas causes these clay soils to shrink in size and become brittle. As a result, a gap opens up between the soil and your driveway, forcing it to sink and crush through the brittle clay. Moreover, occasional rain can cause clay soils to expand up into your concrete driveway, causing even more sinking and uneven sections.