Full scale laboratory testing of ballast and concrete slab tracks under phased cyclic loading

Abstract

Full-scale laboratory-based testing is used to compare the long-term settlement performance of a precast concrete slab track section to a ballasted track (with concrete sleepers) resting on a compacted substructure. The railway track substructure is constructed from a 1.2 metre deep combined subgrade and frost protection layer, according to modern high-speed rail standards such as those specified in Germany. Phased cyclic loading is then used to simulate the primary loading mechanism of a train after 3.4 million load cycles representing train passages. Displacement transducers, earth pressure cells and accelerometers are employed to determine the permanent settlement, the cyclic displacement, transient stresses and vibrations of the track. The equipment, loading combinations, material properties and experimental displacement results are presented and compared. The results indicate that the ballasted track experienced 20 times more settlement when compared to the concrete slab track under the same loading conditions, even though the ballasted track was tested at a slightly higher compacted state due to the concrete slab track test being conducted first.

Dynamic calibration of slab track models for railway applications using full-scale testing

“…In this standard the deflection modulus Ev2 should be at least 60 and 120 MN/m 2 for the subgrade and FPL, respectively. Laboratory tests found the Ev2 value of the subgrade to be 67.71 MN/m 2 and 133.55 MN/m 2 for the FPL [60].…”

“…In this work full-scale laboratory tests of a slab track system are performed comprising the layers represented in Figure 1, namely subgrade, Frost Protection Layer (FPL), Hydraulically Bonded Layer (HBL), bituminous grout layer, slab track (Max Bögl technology), fastening system (Vossloh 300 system) and the rails. A section of concrete slab track, with all the above mentioned layers, was tested at Heriot-Watt University using the GRAFT II (Geopavement & Railway Accelerated Fatigue Testing) test facility [60], which enables to test full-scale railway tracks under realistic railway loading conditions. This rig operates by using six independent hydraulic actuators that load three full-sized sleepers to simulate the passage of a moving train, by phased loading, with each piston applying loads on a given rail segment.…”

Parametric analysis of railway infrastructure for improved performance and lower life-cycle costs using machine learning techniques

“…• The fastening system underneath the wheelset supports 50% of the load, it being assumed that the remaining loads are supported by the adjacent sleepers [11,80]. • The load considered is the maximum load, while the minimum is zero, meaning that the amplitude corresponds to 50% of the maximum load.…”

A shakedown limit calculation method for geogrid reinforced soils under moving loads

“…This loading condition is more challenging to design for compared to static loading, because designs must account for the residual stresses that develop over a large number of loading cycles. Also, when considering methods to improve the load bearing performance of a transport structure under cyclic loading, geogrids are a common solution ( (Dal et al, 2007), (Marolt Čebašek et al, 2018)).…”