Stress Analysis And Experimental Study On Natural Gas Pipeline Under Uneven Settlement

Pipeline transportation of natural gas is one of the main modes. Constrained by geologic condition and engineering practice, many pipelines have been buried in soft soil. With the weak bearing capacity and large deformation of soil under kinds of loads, those pipelines buried in soft soil are prone to be destructed under uneven settlement. Therefore, in the paper, the mechanical characteristics of buried pipelines under uneven settlement are analyzed both in the theory and test.Firstly, based on studying lots of pipelines stress analysis and settlement theories, the formula of mechanical characteristics of buried pipelines under uneven settlement are disscussed. The principles of using CAESAR II to calculate buried pipelines are analyzed.Secondly, on the view of the experiment, in allusion to the NG buried pipelines of valve chamber, the stress test is carried out to monitor the changes of pipelines stress and the settlement test is also implemented. Large amount of test data is very important to the comprehensive analysis of pipelines stress under uneven settlement. From the perspective of software analysis, piping stress levels overall of the valve chamber is calculeted by CAESAR II. Focusing on the zone①and⑦, stress and vertical displacement of pipelines are analyzed on relevant factors such as pipe pressure, tempreture, soil type and different settlement conditions.Finally, combinating of experimental data, theoretical calculations and software analysis a comprehensive analysis is conducted on the pipelines stress and settlement situation. Then the corresponding improvements are put forward. Meanwhile, pipelines protection measures are given out on the design, construction and manufacturing operations acoording to the object of study and characteristics of pipelines engineering. The methods and results of this paper will provide certain theoretical reference and technical support for continuous research on mechanical characteristics of NG pipelines under uneven settlement in the future.