The Extending Features Of The Crack Existed In Continuous Double-block Ballastless Track Based On XFEM

Continuous double-block ballastless track is one of commonly-used track structures in our country’s high-speed railway construction till now. Because of the characteristics of continuous double-block ballastless track and material properties of concrete, there appeared to be many diseases in it. To ensure the durability of the track structure, making effective controls and renovation seems to be extremely important. Of the diseases existed in the track structure the crack is respectively frequent. As with the cracks, making a good knowledge of the propagation properties is the foundation of prevention and repair of them.The paper is dovoted to the study of the extending features of the crack existed in continuous double-block ballastless track by using research methods of other concrete structures for reference. It mainly embark on below three aspects:(1)The data about the diseases of continuous double-block ballastless track was first collcted. And based on the data, a conclusion was done about the crack, including the location, shapes, depth and so on. Accoding to different types of the cracks, the causes are made a physical analysis.(2)Relying on the ABAQUS FEM software platform, the stress intensity factors of a variety of conditions are calculated with the XFEM(extended finite element method) method which is based on fracture mechanics. The influencing factors are made a analysis. By coparing stress intensity factors of the different cracks with fracture toughness, whether they will continue to extend or not can be decided. The results show that the size and the axial temperature loads are the main factors that affect the propagation of the cracks. And the results have a certain theoretical guiding significance about the treatment of the crack disease.(3)By using the finite element mechanical model established, the rule of how the stress intensity factors of crack exsited in the slab varied with different structure parameters can be analyzed. According the rule some feasible suggestions can be told to improve the stability about the cracks by optimizing the parameters of the structure.(3)By using the altered numberical model, the propagation path of the unstable propagation of the cracks can be tracked. Some typical cracks’ propagation are simulated. The results show that the XFEM can be used to predict the propagation path relatively accurate. More analysis was done about the stress characteristics of the slab which have penetrating cracks of different spaces between each in it. The result to it proved reasonableness of the design parameters.