Calculation of a pipe from a polymer material under an external load in a well in the rock mass of permafrost

I. I. Zheleznyak, V. A. Stetyuha

I. I. Zheleznyak, V. A. Stetyuha / News of the Ural State Mining University 3 (2018) 121-125

Relevance of the work is related to the peculiarities of loading the pipe with external pressure in a vertical well located in the rock mass of permafrost. Its results are aimed at ensuring operational reliability and efficiency of geotechnological, engineering-geological and hydro-geological wells.
Purpose of this work is to evaluate the ability of a pipe made of polymer material to bear a load.
Methodology of research. The working conditions of a vertical pipe made of polymer material in wells of various purposes are examined with consideration of the main climatic and geocryological factors typical of the northern part of cryolithic zone of the Zabaikalye Territory. Additional load is set by an external action caused by freezing of water in a closed annular space accompanied by deformation of the pipe when it is compressed by ice. Methods of thermodynamics were used to study the processes. The stressed-deformed state of an elastic model of the pipe made of polymer
material is studied. In determining internal efforts, the LIRA software application was used.
Results. The problem of nonlinear heat and mass transfer in the conditions of permafrost is solved. The pipe is calculated for strength and stability under conditions of its compression by ice in annular space. The dependence of the pipe supporting capacity on its diameter, thickness of the ice layer in the annular space and the characteristics of the material is established. The combination of parameters which can lead to loss of stability of the pipe or to its destruction is defined.
Conclusion. The necessity of the development of special sizes of pipes with a specified wall thickness is justified. This ensures their stability at loading with external pressure when water freezes in the annular space in terms of negative temperatures of the host geological terrain.

Keywords: well, pipe, permafrost, freezing, ice compression, strength, stability.

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