The objectives of this Work
Package are twofold:
1)
Measurement of track response (static and dynamic) in order to
validate the numerical models developed in the project.
2)
Measurements of track response for two retrofitted sites in order to
assess the effectiveness of the grouting methods proposed in this
project. This WP is contributed by all partners and is led by GDS.
The four sites selected
for measurements/monitoring during the project are:
- French site Beugnâtre,
on Paris-Lille high-speed line with train speed of 300 km/h
- French site Zufftgen
on Metz-Lexembourg conventional line with train speed of 140 km/h
- Spanish site
Guadalajara on the new high-speed line Madrid-Zaragoza
- Spanish site Amposta
at the transition zone in the viaduct over Ebro River on
Barcelona-Valencia conventional line
The geotechnical
characterisation of all four sites was completed during the first
two years, the sites are instrumented, and track response
measurements are carried out at these sites.
Operations in
Zoufftgen
A completed renewal of
rail, sleeper, ballast and sub-ballast is performed in November 2003
using the “Puscal IV” maintenance train.
Figure 1: Location of pressure cells under
ballast and along reference sleeper at Zoufftgen
 During
this maintenance operation, measurement devices were placed inside
the track structure, including pressure sensors under the ballast
layer, strain
gauges on the rail and accelerometers inside the sub-ballast layer
and the natural ground, for further measurements (Figs 1 and 2).
Figure 2: Placing of
pressure cells on top of sub-ballast layer at Zoufftgen
A few weeks after the
instrumentation and track works, dynamical measurements are
performed under running trains at various speeds. Instrumentation
device are completed with 3D accelerometers on the sleeper and on
the ground surface, strain gauges on the rail, rail pad deformation
measurements and rail vertical deflection measurements.
From June 29th to July 2nd 2004 a second dynamical
measurement campaign takes place. Measurements are still in
progress.
 Surface
wave analysis technique (SASW) is employed to measure the shear wave
velocity profile of the top 20 meters of the natural soil (Fig. 3)
and a 15m deep core sampling of the natural soil is made for
lithological identification and laboratory testing
Figure 3: Shear wave velocity profile at
Zoufftgen
Operations in
Beugnâtre
The natural loamy soil
of Picardy exhibits weak water sensitive pockets, from natural or
human origins (trenches of WW1) the collapse of which may damage the
track structure.
 In
order to avoid such catastrophic events, it was decided to perform
preventive cement grouting inside these zones anywhere loam collapse
could potentially affect the track integrity. Beugnâtre, at PK 149
from Paris, is one of these grouted spots and is selected for pre-
and post-grouting track behaviour
comparisons. A grouted track section and a
reference track section, out of the grouted area, are instrumented
for dynamical measurements.
The
measurements include track behaviour under high speed trains
(sleeper accelerations, accelerations around and inside the track,
wheel loads, and track deflection) but also under impact hammer and
falling weight tests (Fig. 4).
Figure 4: Falling weight measurement at
Beugnâtre
Grouting operation takes
place in April 2004, on a 20m long section around the measurement
sleeper. Injection boreholes are drilled along the axis of track #1
and on the outer side of track #1. Grouting is successful as it
generates very limited uplift of the track and only localised
ballast pollution.
In June 2004, the
post-grouting tests are performed in order to characterize the
dynamic enhancement provided by the subgrade retrofitting. The tests
include measurement of the dynamic behaviour of the track under
trains, impact hammer and falling weight.
 Long
term permanent track settlements are measured by topographic methods
from June 2003. A moderate settlement (average 0.7 mm) occurs from
June 2003 to January 2004 (Fig. 5).
Figure 5: Track settlement at Beugnâtre from
June 2003 to January 2004
Operations at
Guadalajara
Initially a 120 ton
locomotive is used at this site (Fig. 6). The instrumentation
consists of geophones, accelerometers, LVDTs and laser beam system
(Fig. 7).
Absolute and relative displacements of the rail and sleepers for
locomotive speeds ranging from 0 to 100 Km/h are determined at three
different subsections of this site . The measurements are
used to check the vertical track stiffness at the test site. In
addition, the vertical track deflections produced by daily train
traffic are monitored. For trains passing through the Guadalajara
site at a speed of 200 Km/h absolute and relative displacements of
the different track structure components are obtained and the
contribution of each component to the absolute displacement of the
rail is determined.
Figure 6: Location of locomotive for
static measurements (wheel load 10 tons)
Figure 7: Laser beam system used to measure
absolute displacements of the trail
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