The Energy Needed to Completely Break Down Shear Strength in SW Swedish Clay Utilizing field vane test for determining remoulding energy
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Infrastructure and environmental engineering (MPIEE), MSc
Publicerad
2023
Författare
BERGHEL, MAGDALENA
HAGRYDH, SANNE
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Southwestern Sweden is an area which is prone to landslides due to sensitive clay.
Several notable landslides have been recorded in the region, including the Surte
landslide in 1950 and subsequent events in Göta, Tuve, Småröd, and Lökeberg.
Clays with high sensitivity are sensitive to vibrations and disturbances, which could
lead to a collapse of the microstructure and thus liquefaction. However, sensitivity
alone does not provide a complete understanding of the risks of clay liquefaction and
therefore development of the parameter is needed. The remoulding energy required
to fully break down clay shear strength is a potentially important parameter, and
further research is needed, particularly for Swedish-sensitive clay due to a gap in
the research. Overall, this investigation addresses the need for a comprehensive
understanding of clay behaviour and shear-strength degradation in sensitive clays,
with the potential to enhance the knowledge base for stability assessments and
mitigate the risks associated with the widespread distribution of sensitive clays.
The investigation presented in this thesis aims to estimate the remoulding energy
of clay using field vane tests. The methodology is based on the shear stress and
shear strain behaviour of clay, where the strain energy involved in the remoulding
is assumed to be the remoulding energy. Similarly, this behaviour can be obtained
from vane shear tests. Seven locations from SW Sweden were analyzed, all close to
Gothenburg. The results were correlated to soil parameters obtained from piston
sampling. Additionally, the results were compared to findings of previous research
on Norwegian, Canadian and Finnish clay.
The thesis shows promising results in applying the field vane test to SW Swedish
clay for determining the remoulding energy. The results for southwest-Swedish clay
are of a smaller magnitude compared to previous research on Canadian and
Norwegian clay. The remoulding energy shows correlations to several parameters but
further research is suggested to develop the method and correlations. To further
utilize the method it is important to conduct the field vane shear tests in a consistent
manner. The findings lead to an increased understanding of the behaviour of
clay during remoulding. This can in the future reduce uncertainties and lower the
required safety factors for geotechnical engineering.
Beskrivning
Ämne/nyckelord
field vane test, remoulding energy, shear strength, sensitive clay, sensitivity