Abstract:
Drilled shafts are a popular choice for deep foundations as they can support high axial and lateral loads, and they can be installed with limited disturbance to the surrounding area. Since visual inspection of the completed drilled shaft is not possible, non-destructive test (NDT) methods are commonly specified. Thermal Integrity Profiling (TIP) is a state-of-practice NDT method used for integrity and quality evaluation of drilled shafts, augered cast in place piles, diaphragm walls, and other concrete foundations.
Thermal Integrity Profiling utilizes heat generated during the concrete curing process to evaluate quality. The collected temperature data is combined with installation details to generate an effective radius plot and 3D model. This method can be advantageous to both the contractor and owner based on the ease of installation of the instrumented cables, remote data collection, and reduced time between testing and reporting. TIP results and output models are dependent on proper selection of input parameters to normalize heat dissipation at the shaft ends. There is a perception that TIP cannot thoroughly evaluate the base of a shaft. However, with proper understanding and application of shaft bottom analysis, the full length of a deep foundation element can be effectively evaluated.
This paper includes case histories from Department of Transportation projects in the Midwestern United States where TIP was used to evaluate drilled shafts. Analysis and interpretation of the data will be presented, and focus will be placed on the bottom of shaft adjustment parameters and resulting effective radius model. Data from uniform shafts without integrity issues versus shafts with cored and confirmed anomalies at the base are compared.