Determining Damage Contributions from the Loss or Instability of Soil within a Foundation’s Influence Zone

It is anticipated that structures sitting atop shallow foundations will experience some degree of initial displacement from near surface soil consolidation and/or initial settlement. This paper however focuses on diagnosing one of the causes of displacement that result well after these initial displacements have occurred. In particular this paper focuses on damage contributions from the loss or instability of soil from within a foundation’s influence zone. This paper begins by first identifying a foundation’s influence zone; identified as those soils directly affecting the structure by acting to support and resist its loads. This paper demonstrates how the Boussinesq method, a pre-construction design tool used to calculate the zone of influence (the zone of soil effected by the structure), has been reconfigured for use as a post-construction analysis tool to determine the extent of the foundation’s influence zone, (the zone of soil directly affecting the structure). The reconfiguration consists of breaking down the basic equation and plugging in known values to solve for and ultimately determine the influence zone. This paper concludes by outlining those damages most likely to result from a loss or instability of the soils within a foundation’s influence zone.