Fiber Optic-Based Thermal Integrity Profiling of Drilled Shaft: Inverse Modeling for Spiral Fiber Deployment Strategy

Area of Science:

• Geotechnical Engineering
• Nondestructive Testing
• Sensor Technology

Background:

• Current thermal integrity profiling (TIP) relies on the effective radius method for drilled shafts.
• This method, while efficient, has limitations in accurately predicting the dimensions and shape of shaft defects.
• Advancements in sensor technology offer potential for improved defect detection.

Purpose of the Study:

• To enhance the accuracy of drilled shaft integrity testing by improving defect reconstruction.
• To introduce a novel approach using fiber optic sensors and a spiral deployment strategy for TIP.
• To develop and validate an inverse modeling technique for defect characterization in drilled shafts.

Main Methods:

• Utilized fiber optic sensors for enhanced temperature measurement resolution in TIP.
• Implemented a novel spiral fiber deployment strategy for improved spatial data acquisition.
• Developed and applied inverse modeling based on forward modeling of temperature distribution for defect reconstruction.

Main Results:

• The spiral fiber deployment strategy significantly improves the reconstruction of drilled shaft defects.
• Inverse modeling accurately reconstructs defect details numerically, showing good agreement with forward modeling.
• The enhanced spatial resolution from fiber optics aids in detailed defect characterization.

Conclusions:

• The proposed method advances TIP from a qualitative nondestructive testing approach to quantitative nondestructive evaluation.
• Fiber optic sensors and spiral deployment offer a more precise method for assessing drilled shaft integrity.
• This research provides a foundation for more reliable and detailed subsurface defect analysis in civil engineering structures.