Impulse response function analysis of pore pressures in earthdams

Abstract

In this paper, an Impulse Response Function Analysis (IRFA) method for analysing dam monitoring data is presented. The model developed, which was based on the approximation of the impulse response of the dam, gives the variations in the pore-pressure measurements resulting from changes in the reservoir and tailwater levels. An expression for explicitly estimating the in situ hydraulic diffusivity is presented. Analysis of monitoring data obtained at three dams establishes that with all the instruments used, the data obtained tend to show time lags with respect to the actual changes in the water level. The characteristic diffusion times were found to range between a few days and a few months. The results obtained here show that some essential aspects of the processes observed with most cells and piezometers data can be described in a linear framework and accounted for using this IRFA method with exponential decay.