Enhancing SPT data by reducing uncertainty in energy corrections and leveraging input energy for stratigraphic interpretation

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The Standard Penetration Test (SPT) is one of the most used investigation tools in the world to understand a specific soil's characteristics (e.g. deformability, strength) which are used to design construction projects involving breaking ground. The SPT consists of hammering a sampler into the ground: the number of hammer blows required to drive the sampler a specific distance determines the soil parameters for design. The limitations of the SPT are mostly related to different SPT systems applying different amounts of energy (i.e. force) for each hammer blow. Such energy losses have led to significant uncertainty when correlating soil parameters using SPT, which affect the safe design of earthworks. Although researchers have measured SPT energy losses for a number of systems, the ranges in energy corrections make their application to other systems uncertain.The proposed research aims to enhance an SPT system being used in several projects in western Canada. This SPT system uses automated hammer drops for repeatability and continuous measurements of the energy for each hammer blow. The research will provide measurements of energy loss and a system-specific energy correction that can be used in other projects across Canada. These energy measurements will quantify the variability of the system in terms of the energy delivered, providing a means of calculating the system uncertainty in SPT results. The system-specific uncertainty will be compared against the uncertainty associated with widely used energy corrections to measure the improvements in SPT result confidence.Furthermore, this research proposes to evaluate the suitability of the energy delivered by the SPT (i.e. blows into the ground) as a source for seismic and acoustic tomography of the ground. The enhanced SPT system would improve SPT results for geotechnical practitioners and allow for quick uptake of the results by the geotechnical community in Canada. This will result in increased design confidence for safer geotechnical structures and will allow region-specific correlations between SPT results and soil parameters with higher levels of confidence.