True triaxial testing of geogrid for high speed railways

Yu, Zelong; Woodward, Peter Keith; Laghrouche, Omar; Connolly, David

doi:10.1016/j.trgeo.2019.100247

Cited by 41 publications

(13 citation statements)

References 24 publications

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“…Realizing the potential of geogrids in stabilizing railway ballast, several large-scale model tests were conducted in the past to investigate their role in reducing vertical settlement under cyclic loading conditions. 5–19 Bathurst and Raymond have conducted large-scale model track tests on ballast at loading frequency ( f ) ranging from 0.5 to 3 Hz and highlighted the efficiency of geogrids in reducing the rate of permanent (non-recoverable) settlement generated within ballast. 5 Shin et al.…”

Section: Introductionmentioning

confidence: 99%

Investigation of deformation and degradation response of geogrid-reinforced ballast based on model track tests

Hussaini

Sweta

2020

Proceedings of the Institution of Mechanical Engineers, Part F:

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A series of large-scale cyclic tests was conducted using process simulation test ( PST) apparatus to capture the influence of loading frequency ( f) on the deformation and degradation behavior of ballast with and without geogrids. Fresh granite ballast and subballast having mean particle diameter ( D50) of 42 mm and 3.5 mm, respectively and five geogrids of different aperture shapes and sizes were used in this study. The tests were conducted at f ranging from 10 to 40 Hz and up to 250,000 load cycles. The test results from the laboratory investigations confirmed that the deformation and degradation behavior of ballast is highly influenced by loading frequency ( f). Moreover, the results showed that geogrid reinforcement stabilizes ballast by reducing the extent of lateral spreading ( ld) and vertical settlement ( Sv) and by minimizing particle breakage ( BBI). The inclusion of geogrids also reduces the extent of vertical settlement in subballast layer ( Svsb). In addition, the extent of volumetric ( εv) and shear strains ( εs) including void ratio ( ef) and density ( γbf) were found to be highly influenced by f. It is further seen that lateral spread and vertical settlement reduction index ( LSRI and VSRI) of all the geogrids decreases with the increase in f. Moreover, it is revealed that with the decrease in LSRI, the extent of Sv and BBI increases. A correlation is developed between the deformations ( ld and Sv) and interface efficiency factor ( α). The effectiveness of geogrid in keeping the ballast in place is evaluated in terms of a new parameter ‘geogrid efficiency factor ( Gef)’. The value of Gef for geogrids used is found to vary from 0.02 to 0.27. It is further shown that Gef under cyclic loading conditions is a function of the interface efficiency factor ( α) evaluated under direct shear conditions.

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Section: Introductionmentioning

confidence: 99%

Investigation of deformation and degradation response of geogrid-reinforced ballast based on model track tests

Hussaini

Sweta

2020

Proceedings of the Institution of Mechanical Engineers, Part F:

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“…The geocell [2] applied to the granular foundation layer shows a relatively better improvement, reducing the permanent deformation of the granular foundation and increasing the percentage of elastic deformation [3] . Placing a layer of 0.3m thick reinforced material in the non-woven geotextile [4] and compacting the soil at 97% significantly reduces the penetration force of the CBR piston at all target repeated load levels. Compared with the non-geogrid solution, it is applied to the track structure under pressure [5] , and the geogrid solution reduces the settlement of the structure.…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties of re-packed reinforced Earth embankment during service stage

Hou

Wang

Huang

et al. 2021

Journal of Asian Architecture and Building Engineering

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： Problems of large settlements and uneven settlements on the road always happen during service stage. Reinforced embankments can reduce these problems. But currently the study on the mechanical properties of reinforced embankments during service stage are so few, and lack of measured data. This study uses numerical simulation and on-site measured data analysis to set up a geogrid creep damage model and traffic load model. Based on the analysis of the mechanical properties of reinforced embankment under the conditions of new test section and widening test section, the influence laws of traffic load amplitude, frequency and driving interval on reinforced embankment are obtained. When the traffic load amplitude is 2 0 , there is little difference in settlement between the two test sections, but the settlement ratio gets the maximum value of 0.028 mm/d when the amplitude is 2 0 . When the traffic load frequency increases from 1 Hz to 4 Hz, the embankment settlement is in the sudden settlement stage, and the settlement is almost stable after 4 Hz. When the driving interval is greater than 4 s, the rebound value and rebound time are almost stable.

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“…multiple loads), the critical velocity definition never changes and must remain the minimum speed at which waves commence propagation. Elevated levels of track dynamics are undesirable on railway lines because they pose a safety risk, result in accelerated track degradation [8], and can generate elevated groundborne vibration in the free-field [9][10][11][12][13]. One example of where high dynamic track amplification was recorded is in Ledsgard, Sweden, where shortly after the opening of a new high speed line, abnormally large deflections were measured in the track [14][15][16].…”

Section: Introductionmentioning

confidence: 99%