## 1 Introduction  
As we all know, pipeline engineering is the most economical transportation for oil and gas energy. It is called the lifeline project of oil and gas transportation. The pipeline engineering inevitably goes through permafrost regions and seasonal permafrost regions. Due to the severe cold climate along the pipeline in permafrost regions, the physical state of frozen soil occurs periodic and irreversible frost and thaw under the effect of the cyclical change of the surface temperature and the temperature of the medium in the pipeline [1, 2], the differential frost heave of the soil often occurs. According to the survey, differential frost heave is one of the main pipeline-soil diseases in frozen soil areas. In addition, due to the complex environment in which the frozen soil pipeline is located, there will be many defects in the frozen soil pipeline, which have a decisive impact on the safety and economy of the frozen soil pipeline. Although anticorrosive materials have a certain anticorrosive effect [3], many buried pipelines in service are corroded with the increase of service time. Among the various defects of pipelines in frozen soil areas, internal corrosion defects are an important factor threatening the safe operation of pipelines. When the pipeline is corroded by the corrosive medium in the pipeline, the wall thickness of the local pipeline will be thinned and the carrying capacity will decrease. In severe cases, corrosion perforation will occur [4; 5; 6]. At present, scholars from various countries mainly use finite element simulation analysis and experimental simulation to analyze and evaluate the stress status of pipelines and the residual strength of pipelines with corrosion defects in frozen soil areas [7; 8]. [PERSON] et al. [9] used a combination of finite element simulation analysis and experimental simulation to show that the method based on the full-scale blasting experiment of the sample pipeline may overestimate or underestimate the strength of the residual corrosion pipeline, and then a method based on the [PERSON] criterion to predict the residual strength of the pipeline with long corrosion defects was proposed. [PERSON] et al. [10] studied the residual strength of high-strength pipelines with a single corrosion defect and multiple corrosion defects by using the nonlinear finite element analysis method. The failure pressure predicted by the proposed solution was compared with experimental results and various evaluation methods available in the literature, which proved its accuracy and versatility. [PERSON] et al. [11] used the finite element method to predict the residual strength of externally corroded pipes with ring grooves under internal pressure. The failure trend of annular groove corrosion was determined, and the equation for predicting pipeline failure pressure was established. [PERSON] et al. [12] used ADINA finite element software to establish a three-dimensional model and analyzed the mechanical properties of buried pipelines with internal corrosion defects at the midpoint of the frost-heave section. The results showed that the corrosion depth had a greater effect on the stress-strain of the pipe than the corrosion length. There are mainly ASME B31G-2012 standards, DNV RP-F101 standards and PCORRC methods for evaluating the residual strength of pipelines with a single corrosion defect [13; 14; 15]. Although the application code can be used to calculate the residual strength of the pipeline under various working conditions, the workload is relatively cumbersome, and the stress state of the frozen soil pipeline can not be seen intuitively. In order to analyze the residual strength of the pipeline with corrosion defects in the frozen soil region more reasonably and effectively, the thermo-mechanical coupling analysis of buried non-corroded pipelines is seasonally frozen soil regions was carried out by using ABAQUS finite element software to determine the location of the maximum Mises equivalent stress on the inner wall of buried pipelines in this paper [16; 17].