Empirical prediction of ground-borne vibration from railway systems; validating the HS2 model in Sweden, west coast
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Sound and vibration (MPSOV), MSc
Publicerad
2023
Författare
Nordström, Jim
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Trains are becoming a more and more viable option as a fast, environmentally
friendly travel choice. Along with this cities grows larger and civilizations becomes
more urbanised. This results in an increase of human exposure to vibrations from
trains, creating a need of vibration level predictions. Predictions enables at an early
stage to be able to tell the impact of a new railway system. Whether residence
buildings can be built at a certain proximity to the rail or hospitals, research facilities
with vibration sensitive instruments, what trains with what speeds can pass
and so on. One model to do this is the British empirical model named High Speed
2 (HS2). In Sweden, especially the west coast, the lithology differs from that of the
UK as a result of the melting glaciers. Soft ground material, such as the Swedish
glacial clay have tendencies to generate low frequency vibrational disturbances.
This thesis is an evaluation of the HS2 model under Swedish conditions. It is limited
to predicting the vibration levels in the ground at a certain distance from a surface
running train. In 2021 a thesis work of Gustav Vågfelt was done were the HS2
model was implemented in Matlab and evaluated against a measurement data set
at a Swedish site with help of Efterklang - part of AFRY [1] [15]. This thesis will
continue on that work and in cooperation with Efterklang use the Matlab implementation
to evaluate the model by conducting measurements at two different sites,
one being post glacial fine sand and the other glacial clay. As there are still uncertainties
in the model parameters a final conclusion of its precision can not yet be
set. With the data available however the HS2 performs decent on the fine sand with
quite consistent results and with the evaluation tools a table of values presenting the
expected precision of the model is presented. The HS2 model did however not perform
as well on the glacial clay. Because of this it was extended with an additional
lithology to fit the Swedish glacial clay. This lithology performed excellent for the
glacial clay site measurements, however that is expected as it originated from them.
It was also tested on external measurement data from Greby, Skövde which also
consisted of glacial clay. Here the extension of the model was less accurate. This
indicates that measurement data from more glacial clay ground sites are needed to
get a more accurate model extension.
Beskrivning
Ämne/nyckelord
Ground-Borne Noise and Vibration, High-speed Trains, Railway Sys tems, High-Speed 2 (HS2) Prediction Model, Empirical, Model Evaluation, Low Frequency Vibration, Soft Ground Materials, Glacial Clay.