中文摘要：

针对高速铁路列车荷载激励输入特性及无砟轨道路基在动载作用下的动力响应问题,建立了轨道—路基三维有限元数值模型,确立了单元结构类型、路基本构模型及结构材料参数的选取方法及依据。根据列车荷载分布特点及其激励输入特性,采用2车厢8轮对车辆离散模型,通过Fourier变换获得了相邻车厢两个转向架通过轨道时轨下扣件点的反力时程曲线,在此基础上利用实测数据验证了模型的合理性和适用性。以运行速度300km/h,轴重为170kN的高速列车为例,分别计算CRTSⅡ型板式无砟轨道路基及双块式无砟轨道路基的竖向动应力、竖向动位移及动加速度,揭示上述响应规律与轨道路基结构之间的相关性。

英文摘要：

With the development of high-speed railways,ballastless tracks are widely applied,and the dynamic characteristics of the subgrade form the basis for design,construction,and maintenance of the ballastless track/subgrade system.In a sense,the distribution rule of dynamic response under the action of train loads and the influence of subgrade parameters lags far behind the construction of high-speed railways in engineering because it is highly complicated.The dynamic system,which includes rail,track,and roadbed,is so complex that it cannot be solved by available theory.In this paper,the numerical simulation method is introduced to describe the dynamic action of a roadbed bearing high-speed rail loads.A three-dimensional（3D）finite element model of the track-subgrade system is established with the aid of ANSYS for dynamic response of ballastless track subgrades bearing vehicle dynamic loads and load input behavior.Moreover,by using the choice method and basis of unit type,a constitutive model of subgrade and material parameters is established.According to the distribution mode and behaviors of vehicle dynamic load and load input characteristics,a two-car,eight-wheelset vehicle model was introduced to obtain contact pressure time-history curves of fastening when two bogies pass between neighboring cars through Fourier transform.In addition,the rationality and applicability of the model are verified according to the data obtained from in situ testing.Vertical dynamic stress,dynamic displacement,and dynamic acceleration are calculated for a CRTS II-type slab ballastless track and a double-block ballastless track when a passing train has a speed of 300km/h and an axle load of 170 kN.Furthermore,the relationship between the response laws and the rail-subgrade construction are analyzed.Interrelated analyses reveal that vertical dynamic stress,dynamic displacement,and dynamic acceleration decay with an increase in roadbed depth.Dynamic acceleration decay deceleration was the fastest.In addition,the type of track influence