Research Experiences for Undergraduates (REU), NHERI 2023: Water Content Measurement Calibration for Fly Ash Centrifuge Model During Water Migration

The focus of this project is to develop a calibration procedure for moisture probes used in fly ash centrifuge experiments. Centrifuge experiments allow researchers to physically simulate the behavior of soils deposits under varying conditions. Failure of fly ash impoundments have motivated studies into fly ash containment facilities. Dangerous debris flows after containment failure are caused by the liquefaction of saturated fly ash deposits. The dewatering of fly ash ponds is one strategy for reducing risks and preventing future destabilization. Current centrifuge experiments partly focus on how varying the water table within a deposition can impact fly ash properties. Soil moisture probes are embedded within the model to monitor the fluctuation of the fly ash water contents. This paper will focus on the relationship between readings from the modified GS3 soil moisture probes and the gravimetric water content. Measuring the water content of the tested fly ash, Ash #1, has been challenging due to its unusually high dielectric permittivity levels. Previous attempts to calibrate Ash #1 were not successful due to its unique properties. The calibration curves derived in this project can be used to accurately interpret the sensor readings from previous experiments. The audience for this paper would be geotechnical researchers interested in monitoring the water content of fine ground soils with high salinity levels.