Experimentelle Untersuchung der Anströmung von Vertikalfilterbrunnen

Wells are underground structures for the extraction and pumping of ground water and thus make an important contribution to the global supply of drinking water, agricultural and industrial production. Calculations of the inflowing water amount in the well and the resulting cone of depression are based on simplified assumptions of the model system. Due to steep gradients in the direct vicinity of the well those assumptions often don’t apply. So far differences between theoretical calculations and measured drawdowns are taken into account by applying empirical loss coefficients. Based on extensive experimental studies of groundwater flow in the direct vicinity of the well, this work derives an analytical model of the overall flow processes, taking into account all loss components for confined aquifers. The particularity here amounts to taking into consideration different flow regimes, different porous media, and describing feasible processes at the interface between materials. Initially this work presents and discusses the resistance laws for flow through porous media, which depend on the flow regime. Those laws are then applied to a radial flow system, in this case the groundwater well flow. Subsequently the presentation and systematic evaluation of physical tube well model tests using various samples of porous media in a specially designed cylindrical test facility provide the basis for determining the resistance coefficient of the different sample media. Comparing the resistance coefficients with other studies shows the variability of these coefficients. This variability is taken into account using a probability approach. The fundamental result of this thesis consists of the process-based description of the complete groundwater flow to the well in an analytical model based on the determined resistance coefficient. Finally, the resulting model is applied to an example well used in the dewatering of an open pit mine to assess the impact of individual parameters to the total pressure loss. The results of the physical well model in initial field tests in an open pit mine show a positive result when comparing the pumping rates

Experimentelle Untersuchung der Anströmung von Vertikalfilterbrunnen

Wells are underground structures for the extraction and pumping of ground water and thus make an important contribution to the global supply of drinking water, agricultural and industrial production. Calculations of the inflowing water amount in the well and the resulting cone of depression are based on simplified assumptions of the model system. Due to steep gradients in the direct vicinity of the well those assumptions often don’t apply. So far differences between theoretical calculations and measured drawdowns are taken into account by applying empirical loss coefficients. Based on extensive experimental studies of groundwater flow in the direct vicinity of the well, this work derives an analytical model of the overall flow processes, taking into account all loss components for confined aquifers. The particularity here amounts to taking into consideration different flow regimes, different porous media, and describing feasible processes at the interface between materials. Initially this work presents and discusses the resistance laws for flow through porous media, which depend on the flow regime. Those laws are then applied to a radial flow system, in this case the groundwater well flow. Subsequently the presentation and systematic evaluation of physical tube well model tests using various samples of porous media in a specially designed cylindrical test facility provide the basis for determining the resistance coefficient of the different sample media. Comparing the resistance coefficients with other studies shows the variability of these coefficients. This variability is taken into account using a probability approach. The fundamental result of this thesis consists of the process-based description of the complete groundwater flow to the well in an analytical model based on the determined resistance coefficient. Finally, the resulting model is applied to an example well used in the dewatering of an open pit mine to assess the impact of individual parameters to the total pressure loss. The results of the physical well model in initial field tests in an open pit mine show a positive result when comparing the pumping rates