2533
Adjusting the soil stiffness with stabilisation to minimize vibration at Maxlab IV –
Asynchrotron radiation facility in Sweden
Ajustement de la rigidité du sol par stabilisation pour minimiser les vibrations à Maxlab IV, un
centre de rayonnement synchrotron en Suède
Lindh P.
Peab Anläggning AB, Sweden
Rydén N.
Lund University, Sweden
aBstract: in lund a new next-generation synchrotron radiation facility are under construction, maX iV. this facility requires
extraordinary techniques for the earthworks at site. the vibration requirements are very stringent compared to traditional earthwork
standard. the tolerance is 26 nm (1 s rms above 5 hz) and this requires a very good damping from external and internal vibrations.
different solutions were discussed and simulated during the design phase and the best performance was achieved with a four meter
thick layer of stabilised soil below the concrete foundation. the soil consists of clay till with high clay content. during the design
phase many different binder combinations were tested to meet the design criteria regarding seismic modulus. in order to achieve a
monolith the binders’ setting time was critical since the soil is stabilised in 0.35 meter layers were the next layer are mixed into the
layer below. the binder to best meet both design and construction requirements were a combination of quicklime and ground
granulated blast furnace slag (GGBfs).
rÉsUmÉ : Un nouveau centre de rayonnement synchrotron de dernière génération, maX iV, est en cours de construction à lund. ce
centre nécessite des techniques exceptionnelles pour les travaux de terrassement sur le chantier. les exigences de vibrations sont très
strictes par rapport à la norme de terrassement traditionnel. la tolérance est de 26 nm (valeur efficace 1 s rms au-dessus de 5 hz), ce
qui nécessite un très bon amortissement des vibrations internes et externes. des solutions différentes ont été discutées et simulées au
cours de la phase de conception et la meilleure performance a été réalisée avec une couche épaisse de quatre mètres de sol stabilisé en
dessous de la fondation en béton. le sol se compose de till argileux à forte teneur en argile. au cours de la phase de conception, de
nombreuses combinaisons de liants différents ont été testées pour répondre aux critères de conception concernant le module sismique.
en raison de la réalisation d'un monolithe, le temps de durcissememt était critique puisque le sol est stabilisé en couches de 0,35 mètre
dont la couche suivante est mélangée dans la couche de dessous. le liant qui répondait le mieux aux exigences à la fois de conception
et de construction était une combinaison de chaux vive et de laitier granulé de haut fourneau (slGhf).
KeYWords:soil stabilisation, sesmic testing, vibration, p-wave.
1 introdUction
max-lab is a swedish facility for materials research based on
synchrotron radiation. the new version, max iV, will be 100
times more efficient than any now existing comparable
synchrotron radiation facility in the world. the location of the
new max-lab is placed just outside the city of lund in southern
sweden. the geology consists of 12 to 16 meters of soil (clay
till) on top of the bedrock. close to max iV runs a major
highway which will introduce ground vibrations. since the
facilitiesare sensitive to vibrations an extensive measurmet
program of background vibrations vere executed.
several foundation alternatives vere discussed and some of
them were tested with fem-simulations to determine which
alternative that fullfilled the requrement of damping both
external and internal vibrations. the alternative that best
fullfilled external and internal damping was a 4 meter thick
stabilised layer underneath the concrete slab.
1.1
Geotechnical testing
the pre-investigation of the geology included geotechnical
sounding as well as geophysical measurements as well as core
drilling through the soil layers down into the bedrock. after the
in-situ investigation and evaluation a geological model for the
site was developed. from this model minor excavations were
performed for soil sampling. the soils were classified and an
extensive testing was performed to evaluate which binder or
binder combination that was optimal for the soils. the major
parts of the soils were clay till with layers of silty sand till.
three different binders were tested, lime; cement and slag.
the slag was ground granulated blast furnace slag (GGBfs).
the clay till contained up to 40% clay and the sandy silt till has
low clay content. the high clay content indicated that lime
should be used to break up the clay. however, lime alone would
not work with the sandy silt till. the clay till from this area have
been tested in a earlier study and the combination of lime and
slag was discovered to be efficient in this type of soil (lindh,
2004).two different binder recipes were chosen from the initial
laboratory testing;
cement/slag (80/20)
lime/slag (50/50)
during the construction phase of the mock-up, cement and
slag were chosen due to the current weather conditions and the
time schedule for the mock-up. during the seismic testing of the
mock-up cracks were found in the stabilized material. the
results indicated that the cracks were introduced during
construction of the stabilised layers. the layer in question was
milled 50 mm down into the layer below to ensure interaction
between layers. the binder’s working period was not sufficient
to guarantee that the next layer could be milled into the
stabilised bottom layer without causing cracks. this resulted in
a change of binder to a combination of lime and slag (50/50).
fe-calculations as well as seismic measurements performed
on the mock-up showed that a shear wave velocity needed to be
at least 900 m/s in the stabilised soil.in this case it corresponds
to a compression wave velocity (p-wave) of 1430 m/s. the
seismic velocity testing was performed according to a
methodology developed at lund University and tested on
