Cone Penetration Testing for Illinois Subsurface Characterization and Geotechnical Design

This project sets the stage for implementing a cone penetration testing (CPT) practice in the state of Illinois, providing recommendations for using and interpreting CPT soundings in subsurface investigations. This study also contributes to modernizing Illinois Department of Transportation (IDOT) policy to current CPT-related practices adopted in other departments of transportation, which is consistent with recommendations from the Federal Highway Administration. Toward the goals of this project, CPT soundings across the nine districts of the state of Illinois have been conducted, and available CPT data at IDOT have been evaluated. The generated data have been uniformly processed, generating a database of 156 CPTs distributed across the nine districts. The database also includes shear wave velocity profiles at 28 locations and pore pressure dissipation tests at 45 locations. In addition, information (editable and non-editable) provided by IDOT has been carefully examined. The provided information consisted of boreholes with standard penetration test (SPT) data and laboratory tests on collected Shelby tubes. This information has been used to develop SPT-CPT correlations that can be applied in the state of Illinois and to provide examples of interpreting seismic piezocone test (SCPTu) data in the context of laboratory testing. Due to the several independent, fast, and reliable measurements that can be conducted in a CPT sounding and the fact that they can be done cost-effectively, CPT soundings are increasingly being preferred for in situ testing, and their adoption at IDOT is a positive step forward and consistent with the best practices at other U.S. departments of transportation.