Fabian, Marcus Karl: Near Surface Tilt and Pore Pressure Changes Induced by Pumping in Multi-Layered Poroelastic Half-Spaces. - Bonn, 2004. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5-03724
@phdthesis{handle:20.500.11811/2044,
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5-03724,
author = {{Marcus Karl Fabian}},
title = {Near Surface Tilt and Pore Pressure Changes Induced by Pumping in Multi-Layered Poroelastic Half-Spaces},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2004,
volume = 229,
note = {At three sites in Germany, called OE, BV and WD, pump test experiments were conducted. The aim was the observation and ensuing modelling of near surface tilt and pore pressure changes induced by pumping in nearby wells. The observations were carried out with `bubble tiltmeters' as borehole and platform instruments. The nominal resolution of the instruments was 0.1µrad. Pore pressure changes in the subsoil were recorded through water level fluctuations in wells by means of pressure transducers with a resolution better than 1mm H2O. The model calculations were carried out with the program POEL. With an assumption of a subsoil model, the program allows an accurate and rapid signal simulation. The models are time resolved and account for multi-layered fully saturated poroelastic half-spaces.
At site OE, 12 tiltmeters were used for measurements. They were installed at 16 shallow observation positions. A waterworks was operated at the site and caused pump induced effects. The tilt data was used for imaging the surface deformation fields. This new method of deformation imaging turned out to be promising for further investigations. Heterogeneities in the subsoil might cause disturbances in the symmetry of a surface deformation image. Subsoil consolidation could be monitored and an exhaustion of the lower-lying reservoir might become predictable.
The most striking discoveries are transient pump induced reversals of the tilt signal, which were observed at the locations OE and BV. At BV, the `Noordbergum effect' was recorded in well level data parallel to the tilt reversals. At this site, two tiltmeters were used. The tilt reversals document in the matrix strain the strong coupling between the soil matrix and the pore fluid. This type of signals could be reproduced by poroelastic modelling.
The modelling reveals that the transient signals are sensitive to parameter adjustments in deeper layers of the model. Accordingly, the transient signal part seems generally well suited for a fast experimental determination of effective poroelastic subsoil parameters. Additionally, modelling showed a direct connection between the type of tilt reversal and the arrangement of the layers in the subsoil.
Further aspects of the investigations were: At the site WD tilt observations were conducted with two tiltmeters above a buried quaternary channel from which the groundwater was extracted. Steady state models were calculated for predicting the position and strength of the pump induced tilt maximum at the surface. Refinements of experiments are discussed.},

url = {http://hdl.handle.net/20.500.11811/2044}
}

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