Roadbed Double Block The Ballastless Track Space Mechanics And Crack Characteristics

Bi-block ballastless track is one of non-ballasted track types through the introduction of technology, digestion, absorption and re-innovation, with the construction of a large number of passenger lines, has been more widely used. The bi-block ballastless track's roadbed slab is thick, structural continuity, integrity of location, but the roadbed itself and between new and old concrete interface in the roadbed slab easy to crack. That will affect the appearance and durability of the structure. The biggest drawback of bi-block ballastless track is that it's easy to produce a large number of cracks but not easy to repair, and its durability to be verified. Ballastless durability during service and security has drawn increasing attention. Train load and temperature gradient load can cause Ballastless fatigue in steel and concrete, while the bi-block ballastless spatial mechanical properties of steel and concrete and cracks under a variety of loads are the premise of fatigue durability analysis of the bi-block ballastless track. It has great significance to optimize the design of bi-block ballastless track and guide its maintenance.This paper reviewed the development and applications of the bi-block ballastless track at home and abroad and analyzed the bi-block ballastless cracks features, forms and causes of cracks on the roadbed slab, established the simplified model which considered the resistance between the roadbed slab and the supporting layer, and analyzed the influence of temperature stress and crack due to the constraints between the roadbed slab and the supporting layer.This paper also took the 350 kilometers per hour of bi-block ballastless track on the subgrade by innovation as the research object, according to its structure characteristics and reinforced distribution, the mechanical model was established which could consider cracks in the roadbed in bi-block ballastless track by the large general finite element software ANSYS, then analyzed the mechanical properties of the reinforcement and concrete in the roadbed slab under the train loads, axial temperature load, temperature gradient load and the influence factors when the roadbed slab cracked in some space, by using the established mechanics model.