Foundation stabilization by Thrasher was an integral part of the repair and restoration of the historic Sedalia Public Library.
Parts of the structure had settled 5″.
The extreme drought that began in the late spring of 2012 had devastating effects across the Midwest, particularly on lawns, crops and foundations. One building hit particularly hard was the Sedalia Public Library. Problems were first identified when a construction worker found extremely wide cracks in the foundation in one area of the library. This led to the discovery of other severe foundation issues throughout the library.
“We were told by the structural engineer that we were in imminent danger of collapse.” – Library Director Pamela Hunter, in an interview with KMBC-TV.
A geotechnical engineer was hired by the library to investigate the site subsurface. During the investigation, it was determined that the extreme dryness of the soil around the building’s perimeter was a significant factor in the ongoing foundation settlement. Further investigation revealed that the underlying bedrock had large voids beneath them. These large voids were likely the hidden contributor to the over 5” settlement throughout the years. The recommended solution was to install a customized micropile system so the foundation load would be transferred from the unstable soil to stable bedrock.
Previous attempts by other contractors to correct the foundation settlement included installing extensive supplemental concrete footings, along with an elaborate below-grade watering and dewatering system engineered to control the below-grade moisture. These attempts were unsuccessful, as evidenced by the continued settlement.
Thrasher stabilized the building by first drilling through shallow rock formations and underlying voids into competent rock. Forty-nine high-strength steel resistance piers, with an ultimate capacity of 140,000 pounds each, were then installed through the pre-drilled holes. The piers were then grouted with high-strength grout to add further stability to the system. The interior columns had to be lowered to put the building on a uniform plane. Finally, the unstable soil that had been excavated during installation of the piers was replaced with good fill soil.