既有铁路提速改造是高速铁路建设的一部分。既有铁路提速时，解析路桥过渡段有改良层路基运营后的特殊结构-构造特性，路基中动-静应力场分布是提速改造的前提。但是经典的理论只能对均质路基的变形进行计算，一些能够体现结构-构造对矢量场影响的解析方法只能用于新建铁路路基应力、变形计算，不能反映既有铁路过渡段特殊结构-构造特性的影响。本项研究采用现场原型试验，探索多年运营后过渡段的结构-构造特性。基于层状粘弹性体系和改良土结构损伤理论，建立复柔量表征应力-应变关系的本构方程，在数值仿真模型中加入新构造的影响特性，全面解析新构造作用下路基中动静应力-应变场分布，分析产生新构造的机理和预测新构造的发展。基于已构建的轨道-道床-路基数值模型进行扩展，把新构造作用下轨道的动参数测试数据作为输入，分析提速后轨道的动力响应，反演分析有改良层过渡段路基的临界控制指标，为过渡段路基评价和加固改造提供技术依据与标准。

Existing railway reconstruction for high speed is part of the high speed railway construction. While reconstruction in bridge transition section with improvement layer, the analysis of special structure- tectonic characteristics, dynamic-static stress field distribution and critical control indicators are the base for speed up. However, the classical theory can only calculate the stress and deformation of homogeneous subgrade; some analytic methods can reflect the impact of structure-tectonic, which can only be used to calculate stress-deformation for new construction railway subgrade and not for existing railway. The study exploring structure-tectonic characteristics in existing railway after many years operation with field prototype test. A complex-compliance constitutive equation will be established based on layered visco-elasticity system and improved soil structure damage theory, the dynamic stress-strain field in bridge transition section will be comprehensive analyzed in numerical simulation model by adding tectonic effect characteristics. The new structure-tectonic mechanism will be analyzed and new structure-tectonic development will be predicted combine with the analysis of weathering characteristics on road shoulder. Finite element model will be expanded based on the track-trackbed-subgrade finite element model established by the Ministry of Education Engineering Center in our school, dynamic parameters test data under the new structure-tectonic as input to analyze track dynamic response after speed up. The critical control indicators will be proved in transition with improved layer by inversion-analysis, which is the technical and standard base for transition section subgrade evaluation for speed up.