Research On Design Theory Of Ballastless Track Structure Of High-speed Railway

The research in this paper is under such situations that mass constructions of high-speed railways and passenger traffic railways are being built in our country, with the conditions of the less kilometer number of ballastless track having been laid and a short period of building of the ballastless track along with a systematical and general criterion of design theories on the ballastless track still being absent. Based on the achievements accomplished on the ballastless track both in native and foreign countries, this paper analyzes and researches crucial theories and key technologies confronted with design of the ballastless track, with considering the actuality of our country and railway, and sets up a more perfect system of theories on the design of ballastless track, whose property right will exclusively be owned by our country, which will be used to guide the design of the ballastless track. The main research jobs are showed as below:1. Based on the theory of elastic foundation composite beam, the theory of girder-board-board on elastic foundation, and the theory of girder-solid finite element on elastic foundation, the computable models of ballastless track have been respectively set up. Taken the slab ballastless track as example, the responses of which under train load has been worked out, each feature and limitation of three theories have been analyzed and the applying conditions of each theory have been put forward, then the appropriate calculating theory on design of the ballastless track in our country has been recommended.2. Summarizing and analyzing all kinds of load modes listed on the codes and standards of both native and foreign railway, with considering the actuality situations of rolling and stock and railway traffic organization at our country, and widely consulting various live load modes presently used during the period of design such as the live load mode of showing load of operating locomotive for towing a passenger train, the maximal live load mode of showing the load of high speed train, the mode of showing operating freight train load, the mode of showing track maintenance machine load, and the live load mode of showing China train load, a sort of live load mode specifically right to calculate responses of the ballastless track has been presented for the first time, and the method to calculate design loads of the ballastless track in vertical, lateral and longitudinal aspects have been determined.3. The allowable limit values of deformation of every kind of substructure such as bridge, tunnel and subgrade which served for supporting the ballastless track have been specified respectively, and the calculating methods when considering deformation of each foundation have been presented. Diverse supporting foundations have been wholly considered for the first time, and the changing trends of stress, deformation and some other reactions of structures of the ballastless track stimulated by substructure settlement have been generally researched. The reaction values, which resulted from the finite element analytical method, have been compared with the actual values measured in laboratory experiment and the authenticity of the finite theories and computational results in the paper have been proved.4. The systematically analytical theories and methods which aimed at calculating the deformations of bridge structure have been set up for the first time in the system of design theories on the ballastless track, and the corresponding software has been compiled. By which many influencing factors such as structure weight, construction temporary load, train load, shrinkage and creep of concrete, prestressing force and its loss, uneven settlement of pier foundation and some other causes can be synthetically taken into account, and the responses of bridge such as internal forces and deformations can be worked out at any time from beginning to end of the whole construction or at any time during its using time. Thus the deformations of structure such as the vertical displacement and the turning angle of bridge can be easily worked out, and which build the basis in the design of ballastless track and provide guidance to determine the appropriate time when the ballastless track is needed to lay on the bridge foundation.5. Using the principles of heat transferring, the system info and finite model used to analyze the influence of the ballastless track with the change of temperature have been set up, and the changing trends of internal force, deformation and utilizing performance in ballastless track which accompanied with the change of temperature have been systematically researched. The influences due to the change of temperature in common slab-track have been compared with which in framed slab-track, and the influences of width and thickness of slab to temperature effects of the ballastless track have been analyzed.6. The mechanical behaviors of slab-track and double block track under the load of train have been analyzed, and the moving trends of the responses of the ballastless track accompanied with the changing of parameters such as dimension of structures, fastening stiffness, subgrade flexibility and modulus of elasticity of supporting layers and so on have been researched. By means of which the influence effects of the parameters to the response of the ballastless track under the load of train can be exactly known, thus the reasonable design parameters of the structures of the ballastless track can be determined.7.The creep and shrinkage theory of concrete firstly be systematically introduced to the ballastless track analysis. The analysis models of creep and shrinkage, the analysis method of creep and shrinkage coefficient and the analysis theory of creep and shrinkage in concrete have been researched, the analytical method of creep and shrinkage in the ballastless track has been set up.8. The structure design methods of ballastless track have been studied and the whole design processes of ballastless track have been brought forward. By which the design of ballastless track can be accomplished and the section stresses and fissure width can be check up. Thus a feasible design project meeting with demands of codes and standards can be obtained.