Stress Analysis For Large Diameter Directly Buried Hot-water Heating Pipeline

With the development of urban district heating in China,the application of large diameter pipes(diameter greater than DN1200)for directly buried hot water heating pipes is becoming more and more common.The current technical specifications for direct-buried hot-water heating pipes are only for the pipe diameter less than or equal to DN1200 mm.There is no relevant specification for pipes and pipes with diameter larger than DN1200 mm.In this paper,the stress distribution of Z-shaped elbow,tape pipe and straight pipe buried in the pipe for direct heating is studied in order to provide reference for practical application.Firstly,the stress analysis of heating directly buried hot water pipeline is carried out.The load and failure form of the directly buried hot water pipeline are analyzed,and the ANSYS software used in the research is introduced.Secondly,the stress analysis of the straight pipe was carried out to simulate the influence of pipe wall thickness and cover depth on the stress of DN1400 hot water pipe.The relationship between the length of the maximum transition section and the length of straight pipe section between two adjacent fixed piers is analyzed.Thirdly,the stress analysis of the Z-shaped elbow pipe buried in the heat supply is carried out.The main factors affecting the stress distribution of the Z-shaped elbow pipe are simulated.The results show that the curvature radius and wall thickness of the bend pipe greatly influence the stress of the bend pipe,the maximum appears in the middle of the Z-shaped elbow.The stress of the inner and outer arches is relatively small.When the short compensation arm is less than 0.7 times the length of the deformation section,the maximum stress of the direct buried hot water pipe increases rapidly.Lastly,the stress analysis of the tape pipe was carried out to simulate the main factors affecting the stress of the tapered tube in the anchorage section.The results showed that the length and wall thickness of the tapered tube had a great influence on the stress of the tapered tube.Pipe connections at the pipe stress than bulk pipe joints with large pipe stress.The pipe connections between the small head and the tube are easily damaged.