Study On Freezing Damage Deformation Limits Of Heavy-haul Railway Subgrade In Cold Region

China has a vast territory with a large span and a large number of frozen soil areas.With the rapid development of heavy-haul railway Jointless lines,the deformation of the foundation caused by the freezing damage of roadbeds has become a major engineering problem that needs to be solved in the construction and operation management of heavy-haul railways in cold regions.Subgrade frost damage can cause irregularities in the entire rail and threaten the safety of the traffic.On the other hand,it can aggravate the damage of the line structure itself,affect the safety of Jointless lines,and reduce the service life of the track structure.Therefore,it is of great practical significance and engineering application value to carry out research on the impact of freezing damage deformation of subgrade on the dynamic response of heavy-haul trains and its impact on the safety of Jointless rails,and to determine the freezing damage deformation limit of heavy-haul railway subgrade in cold regions.Based on the investigation and analysis of field test data and related literature data of heavy-haul railway roadbed freezing deformation in seasonal frozen soil area,this paper conducted a study on the impact of heavy-haul railway roadbed freezing damage deformation on driving dynamic response,and analyzed the degree of roadbed freezing.The effects of swelling,thawing and sinking deformation on the broken rails of Jointless rails in winter and the runway expansion in summer are discussed.The specific research content is as follows:First,based on the dynamic and static test data and relevant literature data of the heavy-haul railway field in the seasonal frozen soil area,the freezing damage deformation law and deformation parameter distribution of the heavy-haul railway subgrade in the seasonal frozen soil area were analyzed,and the cosine-like freezing damage deformation model was determined.Secondly,based on the vehicle-track coupling dynamics theory,a multi-body dynamics simulation software UM is used to establish a heavy-haul train dynamics model.The subgrade freezing damage deformation is taken as the research object,and the general route conditions,curved sections,and The law of the influence of the amplitude and wavelength changes of the subgrade frost heave on the vertical curve section on the dynamic performance of heavy-haul trains.The results show that the subgrade frost damage will increase the dynamic interaction between the wheel and rail,reducing the safety and stability of the vehicle.At the same time,based on the train dynamic response index,the limit values of frost heaving and thaw settlement of heavy-haul railway subgrades in cold regions under different line conditions were preliminarily determined.Finally,using finite element software ANSYS,a finite element calculation model of the Jointless track considering the deformation of the foundation is established,and the effects of the uneven frost heave and thawing deformation of the subgrade on the broken track of the Jointless track in winter and the expanded track in summer are analyzed.The results show that Subgrade freezing damage deformation has a greater impact on the safety of Jointless tracks,and the safety of Jointless tracks is affected by the combination of the wavelength and amplitude of the subgrade freezing damage deformation.Based on this,the control limit of frost damage deformation of the Jointless track subgrade in the cold region is discussed.