| Earthquake is a sudden natural disaster,especially destructive to railway track structure.Due to the influence of the earthquake,the track may be deformed and there are different sizes of the horizontal and vertical bending.Sometimes the track structure has not been obviously damaged,but the rail will produce transverse and vertical deformation,which is a threat to traffic safety.Railway is such an important transportation route that it is very important to restore the railway lifeline transportation line as soon as possible.It is particularly important to judge whether the railway line can run safely in time.Therefore,it is necessary to study the influence of the railway deformation on the train safety.In this paper,the following research works are carried out in view of the impact of track deformation on the safety of the train after the earthquake.1.The present research situation of seismic deformation and failure of the track at home and abroad is introduced,as well as the theory and method of the train running safety under the effect of earthquake.The deformation characteristics and causes of seismic track are analyzed,and this paper presents a simulation method of the rail deformation after the earthquake.Combining the existing research results at the present stage,the simulated samples of the post earthquake rail deformation and the original track irregularity are used as the input parameter of the track displacement.The relationship between the size of the track deformation and the railway safety is studied,and the evaluation system of the train running safety is established.2.According to the simulation method of the post earthquake track deformation,the additional upward,downward and undulating deformation of the vertical direction in the different rail lengths is simulated.Based on the evaluation criteria of train running safety,the relationship between the three safety indexes of the lateral wheel interaction forces,the derailment coefficients and the wheel load reduction rates and the additional deformation of the vertical direction is calculated and analyzed in the case of 200,250 and 300 km/h respectively.The results show that with the increase of vertical deformation,the three indicators of traffic safety generally show an increasing trend,and the wheel load reduction rates always exceed the limit requirement first.The vertical upward bending and downward bending deformation have almost the same effect on driving safety,but both are slightly less than the undulating bending.Under the same condition,the shorter range of the vertical rail deformation is,the safer the train will be.The increase of vehicle speed leads to the reduction of the maximum safety deformation.In this paper,the maximum safety deformation of the three kinds of the upward,downward and undulating rail deformation in different speeds is given.3.Considering the different train speed and the rail deformation length,the influence of transverse bending deformation and serpentine deformation on the safety of train operation is studied using the same method for the analysis of the deformation of the vertical orbit.The calculation results show that the safety indexes increase in the different degrees with the augment of horizontal deformation and the train running safety is reduced.At the same time,it is found that increasing the transverse deformation of the same size is more dangerous for the train safety than that in the vertical conditions.The threat of transverse snake shape to running safety is greater than the one-way bending in the horizontal direction.The larger the length of rail deformation is,the greater the allowable maximum safety deformation will be.The influence of the speed on the safety analysis of transverse deformation cannot be ignored.Slight transverse track deformation will lead to derailment at the higher speed.Finally,the maximum safety deformation of the rail in different forms in the horizontal direction is given for 200 km/h,250 km/h and 300 km/h. |
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