Mechanical Performance Analysis And Experimental Study Of Filling Layer For CRTS I Slab Track Structure In High-speed Railway

Compared with ballasted track, non-ballast track has such advantages as stability, stiffness uniformity, good durability, high regularity and less maintenance, etc. It is developed rapidly and widely used because it suits to the high speed and traffic density of high-speed railway in China. Slab track is an advanced structure form of non-ballast track. It is composed of rail, fastener, track slab, filling layer of cement emulsified asphalt mortar (CA mortar) and concrete base, etc. The service performance of the filling layer has great influences on a train's safety and comfort as well as the stability and durability of slab track structure itself. Therefore, in the design of slab track, it is particularly important to grasp mechanical properties and design parameters of filling layer. There is still a lack of complete theoretical system, evaluation methods and experimental verification of high-speed railway slab track filling. The structure design and material selection of filling layer is still in the study.Focusing on CRTS I slab track, a static and dynamic analysis theory of unit slab track with full consideration of filling layer characteristics were established on basis of related research achievements of CA mortar filling layer both at home and abroad. The mechanical properties and parameters of the filling layer were analyzed according to its functional orientation. Then this thesis put forward some guidance for the functions and parameters of CRTS I slab track filling layer. It also studied the design parameter optimization and performance evolution of the filling layer material based on a series of laboratory experiments. The research results were testified and evaluated by dynamics simulation and field dynamic tests in Harbin-Dalian passenger dedicated line. This has provided theoretic support and practical guidance for popularization and application of the filling layer. The main research and results obtained are as follows:1. Space coupling statics analysis method of the unit slab track with full consideration of filling layer characteristics were established.Based on elastic foundation beam/solid theory, a space static calculation model of unit slab track was established by application of finite element method (FEM). And this model fully reflected various performance of the filling layer, such as support, adjustment, buffer, coordination and flexible barrier, etc. The viscoelastic constitutive relation of the filling layer materials was taken into consideration by adopting generalized Maxwell model.2. High speed Vehicle-ballastless track-substructure coupling dynamic theory with full consideration of filling layer vibration characteristics were established.Rolling stock is deemed to be a vibration system of7rigid body and31DOFs linked by a suspension spring and damping. The wheel/rail normal force is determined by Hertz nonlinear elastic contact theory, while creep theory determines the tangential creep force. Rail is viewed as a Bernoulli-Euler beam based on the elastic point support, considering vertical, horizontal and rotational DOFs of the left and right rails respectively. The supporting point space is fastener spacing intervals. Track slab is deemed as vertically an elastic entity on an elastic foundation, laterally as a rigid body motion, considering translational and rotational DOFs, convex block and of CA mortar filling layer provide lateral and vertical nonlinear elastic constraint for track slab. The concrete base is a flexible entity on elastic foundation. And model is proved to be correct and accurate through comparison of simulation results and experimental results.3. The functional orientation, mechanical properties and parameters of the CRTS ? slab track filling layer were systematically analyzed.In order to analyze the mechanical properties of filling layer and its influencing factors systematically, it should be viewed as one of the structural layer in non-ballast track system and carried out the functional orientation analysis. The targeted calculation model was established according to its five functions, i.e. support, load transmission, vibration reduction, vibration isolation, crack resistance. The influence of various filling layer parameters such as thickness, elastic modulus and viscoelastic constitutive relation on its performance was analyzed through a lot of static and dynamic calculation results. Thus, it summatively proposed the functions and parameters guiding recommendations of CRTS ? slab track filling layer.4. The influence of CA mortar filling layer parameters and damages on the dynamic characteristics of the CRTS ? slab track were revealed.High speed Vehicle-ballastless track-substructure coupling dynamic model was used to analyze the dynamic characteristics of the CRTS ? slab track. Combined with static analysis results, the influence of CA mortar filling layer parameters, such as thickness, elastic modulus, and damages, such as slab hanging, mortar filling lack and stiffness uneven, on the dynamic characteristics of the CRTS ? slab track were researched. Research results provide some theoretical support for the detection, monitoring, maintenance and repair works of ballastless track.5.The filling layer material service performance laboratory experiments were carried out systematically. A scale model for CRTS ? slab track was produced to test the track system vibration and noise characteristics under different conditions with various filling layer materials. Then, the filling layer material and construction technology type with good performance of vibration and noise reduction, deformation coordination were obtained. The durability of filling layer materials was tested. Combined with its construction characteristics, performance indicators for the CA mortar filling layer of CRTS ? slab track were put forward.6. Field dynamic performance test research of CRTS ? slab track combined to conduct the dynamics evaluation was carried out.The vehicle and non-ballast track were viewed as an interaction system. The influence of various mortar formulas on dynamic performance of slab track structure was analyzed through field dynamic tests. In addition, under different high-speed condition, impact of the different substructures such as bridge, roadbed and tunnels was tested. According to indicators system of wheel/rail system dynamics evaluation, such as derailment coefficient, wheel load reduction rate, vertical and lateral wheel/rail force, the dynamic strength of the track structural components, etc. the dynamic performance of the track structure and train's running comfort were evaluated so as to provide some theoretical support and experimental basis for the design and optimization of filling layer in non-ballast structural system, and test results verify the theoretical study.