Integrity monitoring of cast in-situ piles using thermal approach: A field case study

•A reliable and efficient anomaly detection approach for pile thermal integrity test is proposed.•A 1D finite element analysis accounted for cement heat of hydration, concrete mix and soil properties is developed.•A linear relationship between maximum temperature and effective pile radius is established through the FE model.•“The effective pile radius” can be reliably used to reconstruct as-built 3D shape and locate defective regions.•The method can identify anomalies inside or outside the pile reinforcement cage and provide quantitively evaluation. A review of the literature shows that pile integrity is a significant concern in pile construction; in particular, determining the location and nature of anomalies along the depth of the piles using thermal integrity testing data. This paper proposes a new anomaly detection approach which combines early-age temperature monitoring data and finite element back-analyses. A case study on a continuous flight auger (CFA) test pile with engineered inclusions was conducted using this new approach. Through 1D finite element analysis, a linear relationship between maximum temperature and effective pile radius is established. A crucial indicator – ‘the effective pile radius’ could be used to reconstruct as-built pile 3D shape and identify anomalous regions inside or outside the pile reinforcement cage. The data interpretation results of the field case study show that thermal integrity testing provides reliable information to identify anomalous regions within the pile. Compared to the conventional cross-hole sonic logging, thermal integrity testing used in combination with the new approach presented in this paper, can provide more reliable information in the pile integrity assessment process.