INVESTIGATION OF MACH CONE DEVELOPMENT IN BALLASTLESS RAILWAY TRACK STRUCTURES OVER SOFT CLAYS
DOI:
https://doi.org/10.11113/mjce.v29.15601Keywords:
Deck track, railway on soft soil, finite element model, ballastless track.Abstract
High speed trains (HST) have many challenges from a geodynamic perspective; such as the case of HST operating in areas with soft soils like soft clays in Delta areas. The speeding trains can easily reach critical velocity due to the resonance of Rayleigh surface waves developed by the train and the low shear wave velocity of the soft soil. When this resonance happens it can develop a phenomenon called “Mach cones†which is similar to the ones the air jets produce at the speed of sound. This phenomenon can be observed in theoretical analytical measurements as well as in practical measurements. This paper studies the occurrence of mach cones in the soft clay soil under ballastless track structure systems and compares this phenomenon with the traditional ballasted track. Results of the displacement contours in the clay layer of the ballasted track show concentric pattern with train velocity of 250 km/h which indicated mach cone development around this velocity. Other ballastless track types modeled show that the displacement contours are distributed with no concentric pattern and indicating no mach cones even with velocities reaching 250 km/h.References
Adolfsson K., Andreasson B., and Zakrisson P. (1999). High Speed Train X2000 on Soft Organic Clay-Measurements In Sweden. 12th European Conf. of Soil Mech. and Geot. Eng. Amsterdam.
Bos J. (2000). Deck Track: Foundation for the Railways of the Future. Holland Railconsult.
Dingqing L., James H., and Chrismer S. (2015). Railway Geotechnics. ISBN: 9780415695015, CRC Press.
El Kacimi A., Woodward P. K., Laghrouche O., and Medero G. (2013). Time domain 3D finite element modelling of train-induced vibration at high speed, Computers and Structures, vol. 118, pp. 66–73.
Esveld C. (2001). Modern Railway Track. vol. Second Edition. Delft University of Technology: MRT-Productions.
Hibbit K. & Karlsson (2000). ABAQUS User’s manual Version 6.1.
Ismail M. (2016). A New Railway Deck-Track in Sinai at East Port Said on Very Soft Clay. Journal for New Generation Sciences, (accepted for publication).
Ju S.H., Liao J. R., and Ye Y. L. (2010). Behavior of ground vibrations induced by trains moving on embankments with rail roughness, Soil Dynamics and Earthquake Engineering, vol. 30, no. 11, pp. 1237–1249.
Karg C., François S., Haegeman W., and Degrande G. (2010). Elasto-plastic long-term behavior og granular soils: Modelling and experimental validation. Soil Dynamics and Earthquake Engineering, 30:635–646.
Lysmer J. & Kuhlemeyer R. (1969). Finite Dynamic Model for Infinite Media. J Eng Mech Div, ASCE 95(4):859–78.
Madshus C. & Kaynia A. (2000). High speed railway lines on soft ground, dynamic behavior at critical speed. J Sound; 231: 689–701.
Madshus C., Lacasse S., and Harvik L. (2004). Geodynamic challenges in high speed railways projects. ASCE Proc Geotechnical Engineering for Transportation Projects (GSP 126).
Peter K., Laghrouche O. and El-Kacimi A. (2013). The Development and Mitigation of Ground Mach Cones for High Speed Railways. 11th International Conference on Vibration Problems, Lisbon, Portugal, 9-12.
Shahin A. (2008). Investigation into Some Design Aspects of Ballasted Railway Track Structure. Dep. of Civil Engineering, Curtin University of Technology, Perth, WA 6845, Australia.
Takemiya H. (2003). Simulation of track-ground vibrations due to a high-speed train: the case of X-2000 at Ledsgard, Journal of Sound and Vibration, vol. 261, no. 3, pp. 503–526.
Woldringh R., and New B. (1999). Embankment Design for High Speed Trains on Soft Soils. Geotechnical Engineering for Transportation Infrastructure, Barends et al (eds), Balkema, Rotterdam.
