Estimation on the influence of seepage on stochastic thermal regime of frozen ground surrounding the crude oil pipeline

Abstract

Abstract There is a lot of rain and snow in Greater Khingan Mountains in Northeast China, and the seepage is obvious for the foundation soils surrounding the crude oil pipeline. In order to estimate the influence of seepage on stochastic thermal regime of permafrost ground, a stochastic analysis of uncertain thermal regime coupled with thermal conduction and seepage is presented in this study. The hydraulic conductivity and thermal parameters are considered as random fields. A stochastic coupling program is compiled by the Matrix Laboratory (MATLAB) software, and the stochastic thermal regime of foundation soils surrounding a crude oil pipeline are obtained and analyzed by Neumann stochastic finite element method (NSFEM). The results provide a new way to predict the stochastic thermal regime coupled with thermal conduction and seepage for the foundation soils in permafrost regions, and it shows that the maximum thawing depth (with seepage) is consistently smaller than the maximum thawing depth (without seepage) on July 15 and October 15, and the maximum thawing depth for the two cases increase with time. With seepage and without seepage, the standard deviations of foundation soils near the crude oil pipeline are roughly the same while the mean temperature have a big difference. The seepage plays a different role in standard deviations for the different time, and the standard deviations (with seepage) are consistently smaller than the standard deviations (without seepage) on July 15 while it is consistently lager on October 15. These results can improve our understanding of the influence of seepage on stochastic thermal regime of permafrost ground in permafrost regions.