Land subsidence caused by pore pressure reduction due to a local groundwater extraction

Abstract

Land subsidence caused by the extraction of groundwater is a well known problem that could cause large and costly damages to the built infrastructure. This master’s thesis explores the land subsidence resulting from reduced pore pressure due to local groundwater extraction in Gothenburg, Sweden. The study employs 1D and 2D consolidation models to simulate the effects of groundwater withdrawal on subsidence, providing a comprehensive analysis of vertical displacements and soil behavior. By integrating geotechnical site characterization with hydrogeological data, the research validates the predictions of the model against field measurements. The findings highlight that the 1D analytical solution correlates well with both the 1D Plaxis model and the field measurements. In addition, the results suggest that the extraction rate is the governing factor for the magnitude of land subsidence at close distances to the pumping well; meanwhile, the clay thickness is the governing factor at further distances from the well. The findings also indicate that the reduction in pore pressure will extend further in the soil profile for thicker clays, resulting in a larger land subsidence over longer periods of time. Furthermore, the findings highlight the need for validation with field measurements and the difficulties of modeling groundwater extraction and predicting subsequent land subsidence using an axisymmetric Plaxis 2D model.