EXPANSIVE SOILS- THE HIDDEN DISASTER

Abstract

Each year, shrinking or swelling soils inflict at least $2.3 billion in damages to houses, buildings, roads, and pipelines-- more than twice the damage from floods, hurricanes, tornadoes, and earthquakes. Yet Washington continues to spend billions of dollars for flood control, but almost nothing to lessen damages from swelling soils. When they are dry, expansive soils are hard and strong, often badly cracking structures built on them. While expansion is more of a problem in arid and semi-arid areas, shrinkage caused by dessication can affect structures in areas with sizeable precipitation. Over 250,000 new homes are built on expansive soils each year; 10% of these will experience severe damage during their lifetime. Expansive soils also damage multi-story buildings. Walls may not be heavy enough to resist soil swelling (uplifting). The same walls are most vulnerable if supporting soil dries out and shrinks, removing wall support.