The Vibrations In Structure And Ground Induced By Track Irregularities

The high speed railways are generally built in a densely populated soft soil areas, the ground vibration induced by them not only affects people’s daily life, but also is extremely detrimental to the production of precision instruments and ancient cultural relics protection. Now, the non-ballasted tracks occupy a large proportion of the proposed high-speed line in the worldwide. However, the scholars can’t fully understand working mechanism and service performance of this new type of track structure, there is an urgent need of a new theory or method to accurately grasp the ground vibration response law of the non-ballasted track line.A new train-track-ground coupling model has been built in this paper. The clear distinction was made between the static axle load and the dynamic load, taking into account the track surface irregularity, and was coupled into2.5-dimensional finite element method. By comparing the smooth and non-smooth track, the wheel-rail dynamic load and the surrounding foundation vibration response laws were calculated. According to the source and path of vibration transmission, then wheel-rail interaction force, the track irregularities, the slab track structure characteristics and the embankment soil properties were all for parametric analyzed. Many useful results have been obtained, providing a reference for the circuit design and circuit vibration assessment for us.The static axle load and the wheel-rail dynamic load induced by track irregularity were clearly separated in the train-track-ground model, so the influence of two forces on the vibration of high-speed rail line could be studied. The multi-rigid-body quarter car model was used for vehicle, the irregularity of cosine form is used for rack surface irregularity, and the single-wheel travel along the single-line model was established. The parametric analysis was used for the influence of the track irregularity wavelength, track irregularity amplitude on the vibration of the structure and foundation. The results of simulation and theoretical prove that the wheel-rail dynamic load was related to the reciprocal of founder, but it was directly proportional to the track irregularity amplitude, thereby reducing the track surface irregularity wavelengths is more pronounced in increasing the wheel-rail force. The shorter the wavelength, the lager the wheel-rail dynamic load forces and the greater the vibration near the track center. The longer track irregularity wavelength, the smaller the frequency of the vibration and the dynamic wheel-rail forces, but the foundation and building vibration around the line were more obvious.In order to study train parameters on the effects of vibration, the Beijing-Shanghai-line model has been established. The response law of the track and ground vibrations induced by the eight CRH3cars at high and low speed using time domain and frequency domain analysis, obtaining that response caused by the length of the single car and the adjacent compartment bogie center distance, and the former was in consistent with measured results in paper of Zhu Sheng Hao.In order to understand track system parameters on the vibration of the structure and foundation, the three-beam system of a simple rail-slab track-concrete base has been established, and was coupled with the lower foundation and2.5D finite element method. The support stiffness and bending stiffness of the slab track were analyzed. The optimal value of the support stiffness and flexural rigidity range of the non-ballasted track characteristics were obtained, providing a reference for the track structure design.In order to study the impact of the embankment body on the structure and foundation vibration, the embankment height was analyzed, and the inherent frequency of the track embankment and the first critical speed has been calculated. When the embankment was only formed with gravel or with the A/B fillers, the embankment on the vibration attenuation is not obvious, and it is significantly when there is improving soil in the embankment, but the higher the embankment, the more land occupation and the lower the first critical speed.In short, the track and embankment structure and train parameters have been analyzed through theory and simulation in this paper, obtaining the first critical speed of the embankment and two importance frequency of ground vibration, so it is important for us with theoretical and practical significance.