Rantaradan kuivatuksen parannuskohteiden seurantamittaukset

Translated title of the contribution: The Follow-up Measurements of Rantarata Drainage test sites

Research output: Book/ReportCommissioned report

Abstract

Three measuring stations were built on the Rantarata railway track in 2017. These
stations measure the displacements and water contents of the sub-ballast layer.
This work presents observations on second measurement period (2020–2022). The
original plan was to implement drainage improvements to the sites in the first
measuring period, but unfortunately, this was not possible. On the timeline of this
report, the drainage was improved only on the site Km44. Both Km44 and Km98
sites have also undergone a superstructure change in 2018.
The drainage improvement, that was carried out at Km44 at the turn of the year
2019–2020, significantly reduced the water content of the sub-ballast layer. In the
past, there was season-related fluctuation in water content, when the saturated
/almost saturated zone in the sub-ballast layer rose to a level of KV-1.0 m. Above
this fully saturated zone, there is a capillary zone with the thickness of 10–20 cm,
where the water content is also higher. This means that the upper part of the subballast layer (intermediate layer), was also on higher water content. After the
drainage improvement, the saturated state was not observed in the measuring
range, which extends up to KV-1.56 The drainage improvement works very well
and the effects on the water content of the sub-ballast layer were considerable.
The installed drain is at a depth of KV-1.85 m at the measuring point (if installed
according to the plans).
The water contents of sub-ballast layers in sites Km98 and km137 were mainly
similar than in the previous measurement period 2017–2019. Km137 is the driest
of the test sites, and increased water contents have only been observed at the
time of the thawing of the frost for some days. Otherwise, the water contents of
the test site have been so low that the structure must be "self-drained". In this
case, the drainage improvement is unlikely to be able to reduce the water content
at Km137. The water contents of the site Km98 vary with the rains, but the water
content of KV-1.0 m and deeper has been close to the saturated state most of the
time. However, in the driest seasons, the water content in this zone has also
decreased, which suggests that the water content can be decreased by improving
drainage. However, the lowering of the groundwater level did not significantly
change the water content of the sub-ballast layer, which refers to several water
zones in poorly permeable soil layers.
There has been no change in the vertical deformation properties of the Km44 site
due to drainage improvements or improvements in the superstructure. The
measured vertical deformations are much larger than average, and the geometry
persistence problem is probably related to the consolidation of the subsoil. The
displacements of the site Km98 were slightly reduced with the change of the
superstructure. The deformation rate in the site km137 have been small and fairly
constant during the measurement history. Based on the results, it is also worth to
pay attention to the success of the tamping, since, despite several tamping
sessions, errors occur in the same places even after the tamping process.
Translated title of the contributionThe Follow-up Measurements of Rantarata Drainage test sites
Original languageFinnish
Number of pages40
Volume66/2023
ISBN (Electronic)978-952-405-108-8
Publication statusPublished - Oct 2023
Publication typeD4 Published development or research report or study

Publication series

NameVäyläviraston julkaisuja
ISSN (Electronic)2490-0745

Keywords

  • Track drainage
  • load bearing capacity
  • Frost heave
  • deformation
  • Water content

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