Finite element analysis of pipeline underpassing high fill based on in-situ monitoring

The safety of oil and gas pipelines has become an important factor influencing the national economy. With the vigorous development of pipeline engineering, oil and gas pipelines often inevitably intersect with various traffic routes. In the western mountainous area of China, it is very common for the oil and gas pipelines undercrossing the high fill embankment, where the oil and gas pipelines generally have a buried depth of 1 m to 3 m, and they are prone to be affected by the uneven settlement of the overlying soil of the upper embankment, resulting in the risk of extrusion shear fracture. Therefore, studying the interaction between the pipelines and the high fill embankment and accurately evaluating their safety have become the essential consideration for oil and gas pipelines crossing the high fill embankment in complex mountainous area. Herein, the stress, strain and deflection response of the pipeline under the high fill embankment of the logistics outer ring road in Guiyang Shuanglong Airport Economic Zone was analyzed with the in-situ monitoring and finite element method, and the threshold of monitoring and early warning was inversely calculated based on the critical instability state of the pipeline. According to the results, the maximum cumulative settlement of pipeline in the study area is 17.3 mm, the maximum difference of uneven settlement is 4 mm, and the maximum internal offset is 16.1 mm, which indicate that the stress, strain and deflection of the pipeline is much smaller than the allowable value, so the pipeline is safe. In general, the research results could provide guidance for the monitoring, early warning and safety assessment of oil and gas pipelines.