Identification and Repair of Karst Subsurface Voids

Construction in karst areas includes the risk of encountering voids in the underlying material. Structures built above voids can experience significant settlement and extensive structural damage. In the most severe cases, the voids may open to the surface, cause catastrophic failure of the structure, and endanger the public. For commercial projects with tight deadlines, identifying potential subsurface voids early in the pre-development stage is critical in being able to provide time for further assessment and for remedial activities to be employed. This paper will be centered on a case study of subsurface voids were identified and remediated on a site planned for the construction of a "Big Box" retail store in Northwest Georgia. The paper will present selected methods for identifying voids and the method selection decision process. It will also discuss the subsequent selection of deep soil compaction grouting to fill the voids, to limit the potential for future karstic effects.