Study on stability of permafrost slopes during thawing

Abstract

A numerical simulation platform that analyzes the variation of the slope factor of safety with time instantaneously is proposed based on heat conduction theory to study the law of stability development of permafrost slopes during thawing. This platform considers ice-water phase change, elastoplastic constitutive behavior and strength reduction in thawing permafrost and can evaluate the factor of safety of permafrost slopes with different slope angles and water contents. Results indicate that under different slope angles and water contents, the evolution of the factor of safety with time displays two stages: nonlinearly decreasing at first and then essentially remaining constant. During the decreasing stage, the plastic slip line overlaps with the thawing front. In this stage, the self-weight of the post-thawed permafrost layer increases continuously while the shear strength of the frozen-thaw interface keeps unchanged. This is the main reason leading to the decrease in the factor of safety. In the second stage, the thawing depth increases continuously while the position of the plastic slip line remains unchanged, resulting in a constant safety factor stage.