Slope Stability Study at Lärjeån - A stability study to evaluate the risk of a landslide occurring for a part of Angeredsbanan located at Lärjeån
Typ
Examensarbete för masterexamen
Program
Infrastructure and environmental engineering (MPIEE), MSc
Publicerad
2021
Författare
Magnusson, Irma
Johnsson, Alice
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The purpose of this Master’s thesis is to conduct a slope stability study regarding the risk
of a landslide occurring, using different calculation methods and a sensitivity analysis. The
calculations are performed using the Direct method and SLOPE/W. Historical research will be
done on how the slope was constructed, together with its effect on the stability. Based on the
slope stability as it is today, various factors that could affect the stability will be studied to
find the most critical changes that could trigger a landslide. Additionally, actions that can be
taken to secure the slope will further be evaluated.
The slope stability is investigated for two sections (840/875 and 875/886) of Angeredsbanan
which is located on a slope, leading down to Lärjeån. The data that is evaluated is retrieved
from field tests conducted by Sweco at the request of Gothenburg city.
For both the Direct method and SLOPE/W, the calculated factors of safety are compared with
the required factors of safety which are set up by the Commission on slope stability. This is
done to evaluate if the slope is safe or not. For the Direct method, three historical scenarios
are set up as different models. The results show that the slope is unsafe for all scenarios. In
SLOPE/W, five historical scenarios are set up. The results show that when excavating the
natural slope it loses some of its stability, going from a stable to an unstable slope. Further
piles were inserted and the slope increased its stability again, reaching the required values for
the undrained analysis for both sections. Lastly, the construction of the embankment was per formed which resulted in a slight reduction of the stability, still reaching the required factor of
safety for the undrained but not for the combined analysis.
When performing a sensitivity analysis to see what possible changes that the slope stability is
most sensitive towards, the natural changes: groundwater level, water level, erosion and the
human changes: embankment height, slope angle, pressure bank and tram load were studied.
The results show that the slope is most sensitive towards erosion when studying the factor of
safety and the rate of change, meaning that this factor is most likely to trigger a landslide on
the site.
Comparing the different actions that could be done to secure the slope, the most profitable
implementation would be to add a pressure bank. This is mainly due to the relatively easy
implementation process connected with the flexible geometry and usage of material together
with the high impact on the stability
Beskrivning
Ämne/nyckelord
Slope stability , Angeredsbanan , Lärjeån , Direct method , SLOPE/W , Sensitivity analysis , factor of safety