Research On Design Theory And Mechanical Properties About RPC Slab Track Of High Speed Railway

For the good stability,high durability and less maintenance of slab track it has been widely used at home and abroad.The slab is the most important part of slab track.At present it usually uses reinforced concrete structure.As mechanical property of common concrete is poor,and the reinforcement is apt to be rusted,etc,all these factors have affected development of slab track.Comparing with common concrete,reactive powder concrete(RPC) possesses more welcome properties such as ultra-high strength, high toughness,and high durability and so on.So if RPC is applied to slab track it can meet the same operating requirements without reinforcements,and make up for the shortcomings of common concrete slab track and improve its performances.Based on the reasons above,the design theory and mechanical property of RPC slab track will be studied deeply in this dissertation.The research works are as follow:(1) Based on the advantages of RPC,considering the stress characteristics of common concrete solid slab and design types of slab in domestic and abroad,the paper has given several preliminary design schemes such as RPC solid,grid and frame,etc.Using ANSYS simulation techniques for entire structure,the paper has built 3D finite element models for slab track of different types.By comparatively analyzing the mechanical behavior,economic performance and technological property,etc,it puts forward that slab track with frame type and variable thickness is the optimal type for RPC slab track.(2) As tensile strength and elastic modulus is higher,the criterion based on strength and stiffness is no longer suitable for RPC slab track.During the design about RPC slab track,elastic design principle should be fully considered on the premise of strength and stiffness.Following this principle design parameters of RPC frame slab track have been analyzed in great detail.The design drawing of RPC frame slab with variable thickness is determined and the suggested values of other design parameters are given also.(3) For the stress along width of frame slab track is unequal,the concept of effective working width is introduced into slab.It is proposed that the beam width should be the value of effective working width but not the whole width of slab when the theory of beam on elastic foundation is used.According to structural and stress characteristics of RPC slab,the model of frame beam on elastic foundation is proposed to be the calculation model of RPC frame slab.Based on the condition of static equilibrium and deformation compatibility,its calculation method is proposed also. (4) According to material properties of RPC and failure characteristics of RPC members, it is detailed to analyze the failure process and stress charateristic of each stage.It is determined that the failure mode of RPC slab can only be tension-destroying.The stress distribution graph and simpified stress graph are given,and according to them the limit state design and calculation mothod are put forward.(5) It is proposed that calculation model of RPC slab track is multi-layer beams model on elastic foudation.According to the theory of frame beam on elastic foudation,the RPC slab track model can be decomposed into longitudinal and transverse parts and then calculated respectively.It puts forward the design theory and calculation method which are suitable for RPC slab track.With the help of Fourier transform,analytical solution on dynamic equations of slab track is obtained,and conventional calculation method and solving method have been improved and modified.(6) A finite element method is applied to analyze the dynamic response of RPC slab track.The slab track,beam and moving load are regarded as a system.Vibration equations of the system are formulated by using the principle of total potential energy with stationary value in elastic system dynamics and the rule of "set-in-right-position". Dynamic performance is studied through self-compiling programm.The results indicate that the RPC slab track is much better than common slab track in terms of dynamic performance.