Potential failure analysis of thawing-pipeline interaction at fault crossing in permafrost

Fault slippage threatens the structural integrity of buried pipelines. In this work, we adopted a 3D thermo-hydro-mechanical coupling numerical model for investigation of a warm steel pipeline crossing active tectonic fault in permafrost, focusing on two pipeline-soil interactions: fault slippage in the course of the thawing of the permafrost and pipeline mechanical behavior. Effects of pipeline fluid temperature, thawed soil permeability as well as faulting regime to longitudinal strain along the pipeline were examined. This study shows that the relatively warm pipeline heats the surrounding soil-ice bonded permafrost, thawing of the permafrost leads to diffusion of the pore fluid surrounding the warm pipeline, and the accumulated pore water near the impermeable freezing front could cause a drastic pore pressure change, which would affect the destabilization of previously stable faults in critically stressed regime. The fault slippage and the corresponding longitudinal strain along the pipeline increase with pipeline fluid temperature and thawed soil permeability, while a relatively larger longitudinal strain takes place in the strike-slip faulting regime.