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

拟议项目的目标是开发高速列车（速度超过400公里/小时）导致的列车轨道-土壤行为预测模型，通过列车速度增加来评估现有基础设施的稳定性，并提出减少振动的补救措施。更好地了解与高速列车引起的振动传播和类似共振状态下土壤性质变化有关的物理现象，以及以最现实的方式对可能有问题的地点进行建模的能力，将使我们能够提出具有成本效益的缓解措施。在此基础上，将建立列车-轨道-土壤相互作用的先进理论和数值模型，以研究铁路基础设施和周围土壤的动力行为。考虑高速列车通行引起的动载作用下轨道和土体的非线性特性，建立了详细的列车-轨道-土体力学模型和相应的数值工具。多层地质剖面将考虑软土材料和不连续面。将彻底调查问题的以下机械方面：高速列车通行下软土地层的非弹性和孔弹性特性，高速铁路在基础设施和非均质地基中的波能局域分布和传播，列车临界速度导致轨道和地基的共振条件和响应放大，以及高速列车加载引起的共振状态下土体性质的变化。开发的数值工具将根据申请人在中国合作伙伴的一个试验场进行的现场测量进行验证和必要时的更新，该试验场在各种底土上建造的高速铁路正在运行。将进行各种现场试验，收集测量数据，并对试验场地的土样进行测试，以获得其强度和变形特性。通过现场和实验室研究，将开发出一种有效的高速列车基础设施预测和评估的数值工具，用于实际应用。

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.