Use of Geosynthetics in Railways Including Geocomposites and Vertical Drains

Indraratna, Buddhima; Rujikiatkamjorn, Cholachat; Nimbalkar, Sanjay

doi:10.1061/41165(397)484

Cited by 6 publications

(3 citation statements)

References 9 publications

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“…This phenomenon was reported by several authors [39,[46][47][48][49][50][51][52]. Basically, the phenomena of interlayer creation and mud pumping are both related to the migration of fine particles and the interaction between ballast and subgrade.…”

Section: Physical Modelling Of Interlayer Creation Of Mud-pumping Phementioning

confidence: 81%

Unsaturated railway track-bed materials

Cui

2016

E3S Web Conf.

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Abstract. Railway track-bed materials are mostly in unsaturated state, and their hydro-mechanical properties depend strongly on their water contents or suctions. In France, problematic soils such as collapsible loess and swelling marl can be origin of instability problems for new lines for high speed trains, while the hydro-mechanical behaviour of interlayer soil formed mainly by interpenetration of ballast and subgrade soil is of concern for conventional lines. In the latter case, the main challenge relies in the large variability of the interlayer soils owing to the variability of natural subgrade soils involved in the railway network. In this paper, a study on interlayer soils is presented, that covers a large spectrum of aspects: geotechnical/geophysical site characterisation, laboratory investigation into the hydraulic behaviour and mechanical behaviour as well as the mud pumping/interlayer creation phenomena, and field monitoring. The combined effect of water content and fines content were emphasized in the laboratory investigation, whilst interaction between atmosphere and track was focused on in the field monitoring. The results show clearly that it is of paramount importance to consider the unsaturated aspect of track-bed materials when analysing the overall behaviour of tracks, in particular when clay is involved in fine fraction.

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Section: Physical Modelling Of Interlayer Creation Of Mud-pumping Phementioning

confidence: 81%

Unsaturated railway track-bed materials

Cui

2016

E3S Web Conf.

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“…The values of stress-dependent stiffness moduli were obtained from previously published results of large scale drained triaxial compression tests under monotonic loading conditions [2]. The hardening soil model showed better agreement with the strain-hardening behaviour of ballast observed in large scale triaxial tests which indicated ballast breakage [26,36,37]. The current formulation of finite element is incapable of conducting post-peak analysis into the strain-softening region, however, in reality, such large strains, or large deformations, are not permitted.…”

Section: Modified Flow Rule Incorporating Particle Breakagementioning

confidence: 99%

“…A total of 4 drain walls were used in the analysis. An equivalent plane strain analysis, with appropriate conversion from axisymmetric to two-dimensions, was used to analyse the multi-drain analysis [37]. In this method, the corresponding ratio of the smear zone permeability to the undisturbed zone permeability is given by:…”

Section: Preliminary Designmentioning

confidence: 99%

Track Stabilisation with Geosynthetics and Geodrains, and Performance Verification through Field Monitoring and Numerical Modelling

Indraratna¹,

Nimbalkar²,

Rujikiatkamjorn³

2012

Int J Railw Tech

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All over the world, ballasted railway tracks form one of the major transportation networks designed to provide heavy haul freight and passenger traffic. However, large cyclic loading from heavy axle trains operating at high speeds often causes excessive deformation and degradation of ballast, as well as unacceptable differential settlement of compressible foundation and, or pumping of the soft subgrade soils. The problem becomes more severe under high impact loads due to rail or wheel imperfections, causing accelerated ballast breakage. A proper understanding of load transfer mechanisms and their effects on track deformations are essential prerequisites for minimising maintenance costs. The field trial at Bulli demonstrated that for trains with wheel flats, extremely high stresses were transmitted to the ballast layer. Installing resilient mats such as rubber pads (shock mats) in rail tracks can attenuate impact forces and consequently mitigate particle degradation. In view of this, a series of laboratory tests were carried out using a unique large-scale drop-weight (impact) rig to evaluate the role of shock mats. The field trial also showed that the moderately-graded recycled ballast, when used with a geocomposite layer, could perform well in comparison with traditionally uniform fresh ballast.Both Class A predictions and field measurements at Sandgate proved that relatively short vertical drains would be sufficient to dissipate cyclically induced pore pressures, curtail the lateral movements, and increase the shear strength and bearing capacity of the subgrade. In summary, this invited Special Paper describes in detail the large-scale laboratory tests imperative for material characterisation, fullscale instrumented field trials for performance verification, elasto-plastic finite element analyses for predicting the behaviour of tracks stabilised using shock mats, and geosynthetic products including grids and prefabricated drains.

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