Towards the numerical ground-borne vibrations predictive models as a design tool for railway linesa starting point

Resumen

In recent decades, High-Speed Railway (HSR) lines have become one of the most extended and environmental-friendly ways to plan new mass transport networks. These systems are directly influenced by its operational speed generated dynamic effects and the areas where it runs through. This necessarily requires to predict ground-borne vibrations generated by trains passing-by populated areas and its influence zone. Trends in ground-borne measurements, prediction models, and isolation systems are usually performed for maximum operation speed. This method implies the maximum dynamic forces which are suitable for structural calculations (generally developed in time domain) but not necessary for vibration related issues (emission and/or transmission). Additionally, these studies are mainly focused on urban areas where maximum operational speed are frequently far from railways service’s top speeds. Related to frequency domain, it is known that upper frequencies are not the most disturbing ones. In fact, European structural standards usually cut frequencies off at 30 Hz, so much relevant information for vibrational prediction is ignored due to it does not influence structural issues. Moreover, current common predictive numerical models usually apply punctual loads (birth & death) that are disposed to run in certain speed conditions. This method, which is considered valid for time domain analysis, are identified to be incomplete for frequency domain components due to its discontinuous application of loads. The implementation of contact theories in the wheel-rail interface implies a continuous load application, refining the obtained results but increasing computational cost. In this study, different scenarios are compared varying inner and boundary conditions of a model, with the aim of validate results and optimize resources by obtaining a parametrical influence study that will show how different assumptions and cases could condition ground-borne vibrational studies results.