Effect of Load Frequency on the Track Rail and Subgrade Layer Settlement

Majeed, Qutaiba G.; Fattah, Mohammed Y.; Joni, Hassan H.

doi:10.36478/jeasci.2019.6723.6730

Cited by 8 publications

(6 citation statements)

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“…The position of the geogrid had no significant effect on the transmitted stresses. Majeed et al (2019) found that the subgrade layer of degree of saturation 100%, there is no effect of the load frequency on the pressure on the subgrade layer when the frequency is less than 8 Hz for the load amplitude 250 and 6 Hz for the load amplitude 200 kN. For 60 and 70% degree of saturation layer, there is no effect of the load frequency on the pressure on the subgrade layer when the frequency is less than 4 Hz.…”

Section: Numerical Settlement Analysismentioning

confidence: 87%

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Experimental and numerical settlement analysis of railway track over geogrid reinforced ballast

Fattah,

Mahmood,

Aswad

2024

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PurposeThe main objective of the present research is to investigate the benefits of using geogrid reinforcement in minimizing the rate of deterioration of ballasted rail track geometry resting on soft clay and to explore the effect of load amplitude, load frequency, presence of geogrid layer in ballast layer and ballast layer thickness on the behavior of track system. These variables are studied both experimentally and numerically. This paper examines the effect of geogrid reinforced ballast laying on a layer of clayey soil as a subgrade layer, where a half full scale railway tests are conducted as well as a theoretical analysis is performed.Design/methodology/approachThe experimental tests work consists of laboratory model tests to investigate the reduction in the compressibility and stress distribution induced in soft clay under a ballast railway reinforced by geogrid reinforcement subjected to dynamic load. Experimental model based on an approximate half scale for general rail track engineering practice is adopted in this study which is used in Iraqi railways. The investigated parameters are load amplitude, load frequency and presence of geogrid reinforcement layer. A half full-scale railway was constructed for carrying out the tests, which consists of two rails 800 mm in length with three wooden sleepers (900 mm × 90 mm × 90 mm). The ballast was overlying 500 mm thick clay layer. The tests were carried out with and without geogrid reinforcement, the tests were carried out in a well tied steel box of 1.5 m length × 1 m width × 1 m height. A series of laboratory tests were conducted to investigate the response of the ballast and the clay layers where the ballast was reinforced by a geogrid. Settlement in ballast and clay, was measured in reinforced and unreinforced ballast cases. In addition to the laboratory tests, the application of numerical analysis was made by using the finite element program PLAXIS 3D 2013.FindingsIt was concluded that the settlement increased with increasing the simulated train load amplitude, there is a sharp increase in settlement up to the cycle 500 and after that, there is a gradual increase to level out between, 2,500 and 4,500 cycles depending on the load frequency. There is a little increase in the induced settlement when the load amplitude increased from 0.5 to 1 ton, but it is higher when the load amplitude increased to 2 ton, the increase in settlement depends on the geogrid existence and the other studied parameters. Both experimental and numerical results showed the same behavior. The effect of load frequency on the settlement ratio is almost constant after 500 cycles. In general, for reinforced cases, the effect of load frequency on the settlement ratio is very small ranging between 0.5 and 2% compared with the unreinforced case.Originality/valueIncreasing the ballast layer thickness from 20 cm to 30 cm leads to decrease the settlement by about 50%. This ascertains the efficiency of ballast in spreading the waves induced by the track.

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Section: Numerical Settlement Analysismentioning

confidence: 87%

“…A full-scale railway track model was simulated by Majeed, Fattah, and Joni (2019) using Abaqus V6.14 program in order to implement the parametric study. A 3D analysis was adopted in this numerical simulation analyses.…”

Section: Numerical Analysis Of Use Of Geotextilesmentioning

confidence: 99%

Experimental and numerical settlement analysis of railway track over geogrid reinforced ballast

Fattah,

Mahmood,

Aswad

2024

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“…The test can start when the load and frequency are adjusted via the data-acquisition system's LCD touchscreen, as needed [44]. Different values are applied for the load and frequency.…”

Section: Procedures For Testing Modelsmentioning

confidence: 99%

“…This type of behavior was observed in both undisturbed and remolded samples. It appears that remolded samples are more resilient to cyclic shear loads [45][46][47].…”

Section: Stresses In the Subgrade Layermentioning

confidence: 99%

Stresses in Saturated and Unsaturated Subgrade Layer Induced by Railway Track Vibration

Fattah,

Majeed,

Joni

2024

Infrastructures

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The theoretical and practical studies of the cyclic loads resulting from the movement and passage of trains on the unsaturated subgrade to determine the effect of the degree of saturation and moisture content on the foundations and infrastructure of the railway lines, especially the settlement in the railway lines as a result of the development of the train loads. Thirty-six laboratory experiments were carried out using models that simulate a railway with nearly half the scale of the real one, using an iron box of (1.5 × 1.0 × 1.0) meters and a layer of clay soil with a thickness of 0.5 m representing the base layer, were constructed inside it. Above it, there is a layer of crushed stone representing a 0.2 m thick ballast, topped by a rail line of 0.8 m long installed on three sleeper beams with dimensions of 0.9 m (0.1 × 0.1 m). The subgrade layer has been constructed at different saturation degrees as follows: 100, 80, 70, and 60%. The tests were carried out using different load amplitudes and frequencies. These experiments investigated the effect of the subgrade degree of saturation on the value of the stresses generated on the surface and the middle (vertical and lateral stresses) and the settlement of the subgrade. In the case of unsaturated subgrade soil, an increase in load frequency has a clear effect on increasing the generated stresses in the subgrade layer, especially with lower saturation levels. However, the results and measurements of these experiments found that the load frequency almost had no effect on the values of the stresses generated on the surface and inside the subgrade layer with a 100% degree of saturation. The results of the investigation demonstrated that, while load frequency had a minimal effect on track-panel settlement, it increased with the load amplitude and subgrade soil saturation degree. The change of settlement of the track panel with the number of cycles has a high rate at the beginning; after a while from that, it decreases gradually until, after some value of the number of cycles, the settlement changes at a very low rate and gradually.

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“…ey indicated that the ballast over the track reduces the dynamic frequency responses. Majeed et al [45] evaluated the effect of the low load frequency on the track rail and subgrade layer to improve the dynamic response and settlement. ey showed that by an increase of the amplitude load and the load frequency, consequently, the settlement of the subgrade layer settlement is decreased.…”

Section: Literature Reviewmentioning

confidence: 99%

Modeling Dynamic Frequency Response on Slab Track of Shinkansen Railway Based on Finite Element Method

Gholizadeh

Aghayan

Hadadi

2022

Advances in Civil Engineering

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The use of slab tracks in lieu of ballast tracks has introduced new dimensions in track dynamics in high-speed railways. To improve the performance of slab tracks under dynamic frequency responses caused by loads on the Shinkansen railway, the present study aimed to investigate the effect of mechanical properties of track components, including the elasticity modulus and thickness on the resonance frequency of the vertical dynamic responses using the finite element method. Such responses included receptance and decay rate in the asphalt bearing layer (ABL), hydraulically bonded layer (HBL), and concrete bearing layer (CBL). In addition, the study sought to select the optimal layer as an effective layer in the view of reducing the resonance frequency of dynamic responses in comparison with the general model. Based on the data regarding the effects of elasticity modulus and thickness of slab track layers on the resonance of the dynamic frequency responses under the amplitude loads, by changing the load from 20 to 25 tons over the slab track, the receptance under the modulus and thickness change increased up to 34 and 29%. Moreover, the decay rate under the modulus and thickness change increased up to 31 and 37%. Accordingly, by increasing the load amplitude, the CBL and HBL showed lower dynamic responses than other layers. Thus, CBL and HBL were selected as the optimum layers for improving the performance of the slab track of the Shinkansen railway.

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Effect of Load Frequency on the Track Rail and Subgrade Layer Settlement

Cited by 8 publications

References 0 publications

Experimental and numerical settlement analysis of railway track over geogrid reinforced ballast

Experimental and numerical settlement analysis of railway track over geogrid reinforced ballast

Stresses in Saturated and Unsaturated Subgrade Layer Induced by Railway Track Vibration

Modeling Dynamic Frequency Response on Slab Track of Shinkansen Railway Based on Finite Element Method

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