Settlement of Structures Supported on Marginal or Inadequate Soils Stiffened With Short Aggregate Piers

A short aggregate pier system, which was developed to provide an economical alternative to the overexcavation/replacement technique, has been used since 1988 to control settlement of structures located at sites with near-surface deposits consisting of marginal or inadequate soils. In this system, highly densified aggregate piers are incorporated within the marginal or inadequate soils, which results in a composite bearing material that is substantially stiffer than the unimproved soil, and on which shallow foundations can be supported with tolerable settlements. Three case histories are described in which the viability and effectiveness of the aggregate pier system in reducing settlements of shallow foundations bearing on the composite material are illustrated. Methods for analyzing and predicting settlements of footings supported on aggregate pier-reinforced soils are also discussed.