作为路桥结合的关键，路桥过渡段的稳定性和强度直接影响到整个路线的平稳性和通畅性。由于多年冻土具有明显的热敏感性和施工过程中对多年冻土的扰动，多年冻土区路桥过渡段的差异沉降比普通地区复杂得多。随着青藏铁路运营年限的增加，道路桥梁过渡段差异沉降问题日益突出。因此，迫切需要研究多年冻土地区路桥过渡段的温度场和变形场。 本文以多年冻土区路桥过渡段为研究对象，运用数值模拟的计算方法，获得了冻土区过渡段横纵断面温度和变形的变化规律，分析路桥过渡段不均匀沉降变形机理，结合目前冻土区过渡段差异沉降的措施和存在的问题，提出了新的改进措施并进行数值模拟，与改进前的温度和变形做对比，验证新措施的合理性。论文的主要工作和成果如下： （1）通过对冻土区路桥过渡段病害调查资料分析，分别总结了过渡段整体的病害的种类和产生原因以及过渡段中路基和桥台变形的分类和影响其变形的主要因素； （2）利用ABAQUS软件对路桥过渡段温度场和变形场进行了有限元数值模拟，分析了路桥过渡段温度和变形的变化特征，可以得出在过渡段纵断面完工20年内高温区分布在桥台表面和路基下部浅层区，横断面中高温区主要分布在路基边坡和顶面的交界处；另外分析了变形场的分布规律，得出在过渡段路基处沉降值要大于其他位置； （3）对当前对于改善冻土区路桥过渡段不均匀沉降所采取的措施进行分析并指出所存在的问题，提出在过渡段做地基处理，也就是在建设时在过渡段底部布桩的措施来解决差异沉降； （4）利用ABAQUS有限元软件通过数值模拟的方法对路桥过渡段温度场和变形场的改进措施进行验证，并与改进前的模拟结果进行了比较。研究表明，施加布桩措施对路桥过渡段差异沉降有很好的控制效果，可以防止过渡段产生严重的变形。 本文的研究成果可以为今后多年冻土区路桥过渡段的设计提供参考。

Roadbed-bridge transition section,which is the key position of a combination of road and bridge, its stability and strength will have directly affect the smoothness and patency of the entire route.Because of the obvious thermal sensitivity of permafrost and the perturbation of permafrost during construction, the different settlements about problems of roadbed-bridge transition section in permafrost zone are more complicated than that in non-permafrost zone. With the increasing operational years of the Qinghai-Tibet Railway, the problem of differential settlement in the transition of roads and bridges has become increasingly prominent,thus it is necessary to carry out the research about the temperature field and deformation field and other aspects of roadbed-bridge transition section in permafrost zone. In this paper, the research focused on roadbed-bridge transition section in permafrost zone,got the variation of temperature and deformation in cross and vertical section of the transition section of permafrost regions by using numerical simulation methods,and analysis of the uneven settlement deformation mechanism of roadbed-bridge transition section.In addition, new improvement measures and numerical simulation are put forward in combination with the current measures and existing problems of the difference settlement of the transition section in permafrost zone.Compared with the temperature field and deformation field before improvement, the rationality of the new measures is verified.The main work and results of the thesis are as follows： (1) Through the analysis of the investigation data of disease in the transition section of road and bridge in frozen soil regions,the types and causes of the diseases in the whole transition section, the classification of the subgrade and abutment deformation in the transition section and the main factors affecting the deformation are summarized respectively; (2)Using ABAQUS software to carry out the finite element numerical simulation of temperature field and deformation field in the transition section of road and bridge,analyzed the variation of temperature and deformation of cross and vertical section in transition section of road and bridge,concluded that after the completion of the vertical section of the transition section within 20 years, the high temperature area of the vertical section is distributed in the surface of the bridge abutment and the shallow area of the lower part of the subgrade, and the high temperature area of the cross section is mainly distributed at the junction of the subgrade slope and the top surface;in addition, the distribution of deformation field is analyzed, and it is concluded that the settlement value at the subgrade of the transition section is greater than other positions; (3)Analyzing on the measures taken to improve the uneven settlement of the road and bridge transition section in frozen soil region and pointing out the existing problems,this paper puts forward making foundation treatment to deal with the differential settlement in the transition section,that is, to arrange piles at the bottom of the transition section during construction; (4)The temperature field and deformation field of the road and bridge transition section with improved measures are simulated by ABAQUS finite element software,and the simulation results are compared with those with no measures before the improvement.The results show that the pile placement can control the differential settlement of the transition section of the road and bridge and prevent the serious deformation of the transition section. The research results of this paper can provide some references for the design of road and bridge transition section in permafrost regions in the future.