Modelling the density-driven discharge of sandstone blocks

Abstract

The density-driven discharge of salt-laden sandstone blocks has been studied to provide a knowledge basis for the prediction of the contaminant release of abandoned mines when they are flooded. To this end the results of a model experiment, of simplified analytical models and of numerical simulations in 1D, 2D and 3D have been analysed. Simple analytical functions have been found which approximately describe the time-dependent discharge of salt mass at complete saturation. They depend on the material parameters, the dimensions and the outflow geometry of the blocks. The discharge through the basal face is described well by an exponential behaviour. If the outflow occurs solely through the lateral block faces an algebraic function has been fitted to the simulated curves. In this case similarities to directed transport models of statistical physics have been pointed out. The results facilitate the superposition of discharge functions for single sandstone blocks to yield the discharge behaviour of the whole mine.