Centrifuge modelling of train passage over clay subgrades

TY - GEN

T1 - Centrifuge modelling of train passage over clay subgrades

AU - Robinson, Scott

AU - Brennan, Andrew

AU - Munro, Cameron

AU - Woodward, Peter K.

AU - Connolly, David

AU - Laghrouche, Omar

AU - Esen, Ahmet

PY - 2020/9

Y1 - 2020/9

N2 - The modelling of large geotechnical structures on the centrifuge is now well established, but there remain technical challenges with each new application. This work arose from a larger project investigating alternative improved embankment designs. The project required full scale modelling of new embankment designs using the GRAFT II simulator at Heriot Watt University together with consideration of the large scale settlement problem over a wider area. To model foundation soil beneath the embankment required the design of a rail simulator at centrifuge scale, together with appropriate measurement techniques and appropriate modelling of useful foundation soil types. This paper therefore describes the design decisions taken to produce a centrifuge mounted rail simulator including details of modelling a translating cycling load. To measure total stress at the base of the embankment during a train passage was a key challenge faced, overcome by use of thin Singletact stress transducers. These transducers are low deflection capacitance-based force sensors that will be further discussed in the paper. In addition to the translating load and the instrumentation, the third aspect presented will be the formation and characterization of a soft clay subgrade, required due to the nature of soils that are most of concern to UK rail industry. To accelerate consolidation without compromising the ability to achieve a clay-type mechanical response, a hybrid clay-sand-silt mixture known as KSS 541 is installed in the model container as slurry and consolidated in-flight. Experience with this material is discussed.

AB - The modelling of large geotechnical structures on the centrifuge is now well established, but there remain technical challenges with each new application. This work arose from a larger project investigating alternative improved embankment designs. The project required full scale modelling of new embankment designs using the GRAFT II simulator at Heriot Watt University together with consideration of the large scale settlement problem over a wider area. To model foundation soil beneath the embankment required the design of a rail simulator at centrifuge scale, together with appropriate measurement techniques and appropriate modelling of useful foundation soil types. This paper therefore describes the design decisions taken to produce a centrifuge mounted rail simulator including details of modelling a translating cycling load. To measure total stress at the base of the embankment during a train passage was a key challenge faced, overcome by use of thin Singletact stress transducers. These transducers are low deflection capacitance-based force sensors that will be further discussed in the paper. In addition to the translating load and the instrumentation, the third aspect presented will be the formation and characterization of a soft clay subgrade, required due to the nature of soils that are most of concern to UK rail industry. To accelerate consolidation without compromising the ability to achieve a clay-type mechanical response, a hybrid clay-sand-silt mixture known as KSS 541 is installed in the model container as slurry and consolidated in-flight. Experience with this material is discussed.

KW - Centrifuge modelling

KW - Railway Embankment

KW - Railway track settlement

KW - reinforced soils

UR - http://ltu.diva-portal.org/smash/get/diva2:1404151/FULLTEXT01.pdf

M3 - Conference contribution

SN - 978-91-7790-542-4

SP - 185

EP - 192

BT - Proceedings of the 4th European Conference on Physical Modelling in Geotechnics

A2 - Laue, Jan

A2 - Bansal, Tarun

CY - Lulea University of Technology, Sweden

T2 - 4th European Conference on Physical Modelling in Geotechnics

Y2 - 6 September 2020 through 8 September 2020

ER -