Thermal integrity profiling for augered cast-in-place piles - implementation plan.

PDFTech ReportBDV25-977-34Piles (Supports)Shaft sinkingAugersCast in place concreteAuger-cast pilethermal integrity testquality assuranceDrilled shaftsaugered cast-in-place pilesFloridaUnited StatesFlorida. Dept. of TransportationMullins, GrayJohnson, KevinUniversity of South Florida. Dept. of Civil and Environmental EngineeringFlorida. Dept. of TransportationUS Transportation CollectionThis study was the second in a two-part research program focused on assessing the feasibility of using thermal integrity profiling (TIP) as a quality assurance tool for Augered Cast-In-Place (ACIP) piles. This was made possible by coordinating with the Deep Foundations Institute (DFI) ACIP pile project to demonstrate the strength of the piles in various loading conditions (i.e., tension, compression, and lateral loads), as well as overall pile integrity and the effectiveness of TIP for ACIP piles. In all, seven test piles were equipped with thermal integrity assessment devices. Both probe and thermal wire systems were used to collect data over an extended period of time, thereby providing a means to compare instrumentation methods, schemes, and analysis techniques. One of the seven piles was extracted to assess the validity of on-site inspection methods. The extracted pile was also used as a control for the thermal analysis comparison. Results from thermal integrity profiling showed promising capabilities to verify the integrity and profile of the as-built piles. Analysis methods that were hypothesized in the original study were vetted and showed good agreement with the physically verified true pile size, shape, and integrity. These methods were further refined to minimize errors associated with simplistic linearization of the inverse hyperbolic tangent relationships. Both probe and wire systems were shown to provide the same data; however, wire systems have the distinct advantage of reducing cage/reinforcement congestion. PVC access tubes were also shown to be better for small volumes of grout that can be vulnerable to heat sinking with steel tubes. Like most new developments and the additional information provided for the contractor, thermal profiling has shown that single bar reinforcement is often eccentric and that tighter centralizer spacing would be beneficial. The shape of the pile predicted by thermal evaluation mimicked the actual pile closely but accurate determination of grout volumes directly affects the thermal analysis results. As such, it is a critical factor in the entire ACIP pile quality assurance program, and improvements are needed in this determination