System dynamic behavior of high-speed railway infrastructure on multilayered soils considering soil nonlinearities

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The objective of the proposed project is to develop models for prognosis of train-track-soil behavior due to high speed trains (velocity over 400 km/h), to evaluate existing infrastructure in the context of infrastructure stability by a train speed increase and to propose vibration reduction remedies. An improved understanding of the physical phenomena associated with transmission of vibrations induced by high speed trains and variation of soil properties at resonance-like state and the ability to model in the most realistic way potentially problematic locations would allow us to propose cost effective mitigation measurements. Along these lines, an advanced theoretical and numerical model for the train-track-soil interaction will be developed in an attempt to study the dynamic behavior of railway infrastructure and the surrounding soil. A detailed train-track-soil mechanical model and the accompanied numerical tool will be constructed taking into account the nonlinear behavior of the track and the soils under dynamic load induced by high-speed train passage. Multilayered geological profiles will be taken into consideration with soft soil material and discontinuities. The following mechanical aspects of the problem will be thoroughly investigated: i) inelastic and poroelastic behavior of the soft soil stratum under high-speed train passage, (ii) wave energy localized distribution and propagation from high-speed railway in the infrastructure and inhomogeneous soil foundation, iii) critical velocity of the train which leads to resonance condition and response amplification of the track and the soil foundation, and (iv) variation of soil properties at resonance state induced by high speed train loading. The developed numerical tool will be validated and where necessary updated based on in-situ measurements conducted by the applicants in a test site of the cooperation partner in China, where high speed railway constructed on various subsoils is in operation. Various in-situ tests will be performed, measured data will be collected and soil samples from the test site will be tested to obtain their strength and deformation characteristics. By means of in-situ and laboratory investigations, an efficient numerical tool for prognosis and evaluation of high-speed train infrastructure will be developed for practical applications.