Analysis of the stress-deformed state of pipelines during plunging

Abstract

Recently, there has been a need to carry out work on deepening the pipeline (plunging) in some areas, where the depth of pipeline location was found to be inconsistent with the relevant standards. That is, pipelines during operation can be partially opened as a result of soil erosion, and they also tend to lose stability as a result of various factors (pressure, temperature, soil water content, etc.) and rise up (float). Also, the facts of laying pipelines in the process of their construction not to the design marks are known, due to the "low" construction conduct, that is, when the pipeline in some sections was in a trench, the depth of which did not correspond to the project. Further operation of such pipelines may be under the threat of the pipeline coming to the surface and mechanical damage to the insulation and the pipe body. Therefore, to ensure reliable operation of the pipeline, which has got raised sections, it is necessary to lower these sections to the design marks. To do this, it is necessary to develop equipment
and technology for repair work of this type. Therefore, the article considers two options for post-trenching
pipelines: lowering under its own weight without supporting and lowering with the maintenance of the pipeline by a supporting machine. For both methods of plunging, the stress-strain state of the pipeline was simulated during its lowering to the design level on the created mathematical model. An algorithm for calculating the geometric parameters of work performance, determining the stress state and checking the strength of the pipeline has been proposed.