Reasonable Format Of Ballastless Track Piled Slab Subgrade Structure Research

According to the latest regulation of China's railway, railway construction (2009) 209 high speed railway design specification (try out):ballastless track subgrade settlement after accomplished should satisfy ability for the fastener adjustment and the requirements of vertical lines curvature, and post-construction settlement. The different settlement of roadbed and bridge, tunnel or horizontal structures should not be more than 5mm, the fold angle caused by uneven settlement not should be more than 1/1000. Therefore, it's difficult for conventional foundation treatment to meet high smooth, high safety and high comfortable for the standard of high speed railway. Embankment, as a foundation under track, controlling its settlement, especially post-construction settlement is very important for high-speed railway.Piled slab structure is a new structure form under track that is proposed to solve the settlement control problem, and its limited application had shown very good technical and economic benefits. However, the current research on piled slab structure subgrade in our country is still in the primary stage. Each passenger special line has their own structure forms according to the natural geographical background and geological conditions, which causes the current piled slab structure has no unified using standard. The design theory is not mature, service performance and mechanical characteristics are not clear, thus it's necessary to do some further research on it. Through the numerical calculation and simulation analysis, this paper researches the main pile board structure form at home and abroad.1,This paper collects the domestic and foreign information applied in piled slab structure, and sums up those as three main forms:independent pier-pillar piled slab structure, bearing bridge piled slab structure and buried piled slab structure.2,Based on the structure mechanics knowledge, this paper simplifies the entity structure into plane truss structure common seen in structure mechanics, and simplifies external loading which is applied on entity structure into concentrated load or line load which is applied on the truss plane. Using structure mechanics solver, the article analyses these statically indeterminate structure in all kinds of effects (external force, the temperature effect, bearing deformation, etc) under the action of the response, the internal force calculation (including shaft force, shearing force and bending moment), the displacement calculation (line displacement, angular displacement) are also included.3,Depend on finite difference software FLAC3D, this article sets up simulation models for the three piled slab subgrade structures. Through speed of 250 km/h and speed 300 km/h two conditions, the paper respectively calculates the load effect to piled slab subgrade structure produced by train axle load and dynamic excitation force, summaries pile--soil stress variation regulation along the pile body and bearing plate deflection and tensile stress variation regulation. By comparing the stress and displacement of three main bearing structures, this paper finally gives out the elected result, which is useful for related design and construction.