Evaluation of the streaming potential effect of piping phenomena using a finite cylinder model

Piping phenomena into the upstream face of an earth dam can be approximated by a finite cylinder model. A formula of the streaming potential (SP) effect of such a model was developed by integrating an equation of an infinite cylinder section. Numerical modelling allows the conclusion that the oblong SP field shape of a model is only for relatively long and shallow piping models. The SP field shape of a model can actually be circular below a certain ratio value between the depth and length of the model. The resulting SP field of a finite cylinder is symmetrical with respect to its middle point, which allows, in some cases, reaching conclusions about piping phenomena outside the measured area. inite cylinder formula needs smaller values of moments of polarisation to generate SP data almost identical to the SP magnitudes obtained from the expression of an infinite cylinder section. om component was added to the SP effect of several computed models. Relatively short and deep piping phenomena can pass unnoticed, especially for a low signal-to-noise ratio. However, detection of anomalous patterns can be improved if the measured data are pre-processed according to a “studentized” deviate concept, which is then subjected to a statistical test based on the Chebyshev inequality. d example of an SP piping process was detected at the upstream face of an earth dam. Its existence was also confirmed by a geoelectrical survey.