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A New Thermal Integrity Method for Pile Anomaly Detection



Anomaly detection is a hot topic in pile construction which is a complex one due to the intrinsic nature of underground structures, such as limited accessibility, large depth and complex soil profile. Several traditional pile integrity tests have been developed before, which, however, cannot give detailed information of anomaly size, nature or precise location. This paper proposes a new thermal integrity testing method that employs distributed temperature sensors and combines concrete heat hydration numerical model. The fundamental principle is that early-age concrete releases heat during curing. If defects such as voids, necking, bulging and/or soil intrusion exist inside the concrete body, they will result in local temperature variations. The developed numerical model uses Finite Element Method (FEM) to simulate concrete hydration and heat transfer. The model can be customised for different concrete mixes, pile geometries and built-in anomalies. The modelling results are then compared to field test temperature data. Any temperature disparities indicate potential anomalies of the pile structure. The proposed new test will reduce the cost and increase the accuracy compared to traditional integrity tests. It will be a promising method for the future deep foundation assessment.


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