| China’s western part of the construction of a mountain meter track railway project,using the form of ballasttrack,and the whole line laid seamless line.Due to the short route mileage,the high and low difference of the starting point and the harsh terrain conditions,it is inevitable that there are many large ramp sections,among which the largest ramp reaches 250‰.In the large ramp section,the ballast bed resistance to maintain the stability of the track structure will be reduced,on the other hand,the stability of the ballast bed itself will be weakened.Obviously,the stability of track structure is the key problem in the construction of mountain meter-gauge railway.At present,there is no systematic theoretical research on the meter-track ballasttrack with large ramp at home and abroad,let alone the forming technical specification.Therefore,it is necessary to carry out systematic research in order to provide theoretical guidance for the design and construction of the meter-track railway in mountainous areas.In view of this,based on the meter-gauge railway under construction,this paper carries out a study on the structural stability of meter-gauge ballasttrack with large ramp through laboratory tests and numerical calculation methods such as discrete element and finite element.The main contents are as follows:1.According to the relevant parameters of the meter-gauge railway under construction,a full-scale test model is built in the room to carry out the resistance test research on the ballast track bed of the meter-gauge ballast-track and obtain the resistance parameters of the concrete sleeper bed of the meter-gauge.2.PFC3D is used to establish a discrete element model of meter track ballastless track with the same size as the test model.This model is used to restore the indoor ballast bed resistance test and verify the correctness of the discrete element model and parameters.At the same time,the finite element model of the meter rail structure was established,and the longitudinal numerical simulation of the rail structure under longitudinal load was carried out simultaneously with the discrete element model,which verified the correctness of the model.3.Numerical simulation with discrete element method was carried out to obtain the ballast resistance parameters of the concrete sleeper with different slopes.The results showed that the ballast resistance of the concrete sleeper with the gradient increased significantly,and the reduction ratio was greater than that of the slope cosine.Then finite element method and discrete element method are used to study the longitudinal stability of meter-gauge track structure under different slopes,and the slope limit value is obtained.Under the condition that the resistance parameters of the track bed have been obtained and the correctness of the finite element model has been verified,the more efficient finite element method is used to carry out numerical simulation on the lateral stability of the curved section of the meter-rail railway with large ramp,and the recommended values of the curve radius under different temperature conditions are obtained.4.In order to further study the long-term stability of meter-track track with large ramp,the study on the variation law of resistance of track bed with ballast track with different slope under the action of train load cycle and the overall stability of track structure was carried out.The results show that the resistance of track bed will be increased to a certain extent under the long-term action of train load,and the track structure will have a large longitudinal displacement,affecting the stability of the track structure.According to the long-term stability analysis results of the track structure,the slope limit is obtained.Finally,the variation law of the resistance of the track bed with longitudinal reciprocating displacement is studied,and the influence of the displacement variation rate,displacement amplitude and slope on the resistance of the track bed is analyzed. |
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