Estimation of pore pressure levels in slope stability calculations: Analyses and modelling of groundwater level fluctuations in confined aquifers along the Swedish west coast
Swedish title: Estimation of pore pressure levels in slope stability calculations: Analyses and modelling of groundwater level fluctuations in confined aquifers along the Swedish west coast
Author Håkan Persson
Series: SGI Rapport
Chalmers University of Technology. Department of Civil and Environmental Engineering. Division of GeoEngineering. Licentiate thesis 2008:11
The stability of clay slopes often depends on the current pore pressure levels, where high pressure levels are associated with low stability. In Sweden there is a recommended method for estimating the maximum pressure levels but for various reasons, discussed further in the thesis, this method has not become established. In this study several areas of improvement for the method recommended have been identified. Further, a classification system for groundwater level fluctuations in confined aquifers is presented. The classification is based on commonly available topographical and geological information and has been developed from analyses and simulations of groundwater level fluctuations in three study areas on the Swedish west coast. The model used in this study is a slightly modified version of the hydrological HBV model. Even though the use of the modified HBV model, for the purpose of groundwater level calculation, involves a highly conceptual description of the processes involved, the simulation results are promising. Calibration simulations show that the observed groundwater level variations in confined aquifers can be described satisfactorily. Furthermore, validation simulations show that even with little hydrogeological information of an area, groundwater levels can be simulated reasonably correctly using the model. In addition, preliminary climate change simulations, using the modified HBV model, indicate that the overflows in the confined aquifers govern the maximum levels, meaning that increased precipitation has limited influence on the groundwater levels. These simulations should, however, not be interpreted as predictions but more as an indication of an area of application for the model.