Impact of Climate Change on the Performance of Permafrost Highway Subgrade Reinforced by Concrete Piles

• Published in: Future Transportation
• Main Authors: Yueyue Wang, Ying Zhao, Xuesong Mao, Shunde Yin
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2023
• Subjects: transportation and pavement engineering; highway subgrade reinforcement; freeze–thaw cycles; soil-pile interface; permafrost thawing; climate change; Engineering (General). Civil engineering (General); TA1-2040; Ice; permafrost
• Online Access: https://doi.org/10.3390/futuretransp3030055; https://doaj.org/article/5952ae90a16e4cfa8d3774ea2819819a

Climate change has a detrimental impact on permafrost soil in cold regions, resulting in the thawing of permafrost and causing instability and security issues in infrastructure, as well as settlement problems in pavement engineering. To address these challenges, concrete pipe pile foundations have emerged as a viable solution for reinforcing the subgrade and mitigating settlement in isolated permafrost areas. However, the effectiveness of these foundations depends greatly on the mechanical properties of the interface between the permafrost soil and the pipe, which are strongly influenced by varying thawing conditions. While previous studies have primarily focused on the interface under frozen conditions, this paper specifically investigates the interface under thawing conditions. In this study, direct shear tests were conducted to examine the damage characteristics and shear mechanical properties of the soil-pile interface with a water content of 26% at temperatures of −3 °C, −2 °C, −1 °C, −0.5 °C, and 8 °C. The influence of different degrees of melting on the stress–strain characteristics of the soil-pile interface was also analyzed. The findings reveal that as the temperature increases, the shear strength of the interface decreases. The shear stress-displacement curve of the soil-pile interface in the thawing state exhibits a strain-softening trend and can be divided into three stages: the pre-peak shear stress growth stage, the post-peak shear stress steep drop stage, and the post-peak shear stress reconstruction stage. In contrast, the stress curve in the thawed state demonstrates a strain-hardening trend. The study further highlights that violent phase changes in the ice crystal structure have a significant impact on the peak freezing strength and residual freezing strength at the soil-pile interface, with these strengths decreasing as the temperature rises. Additionally, the cohesion and internal friction angle at the soil-pile interface decrease with increasing temperature. It can be concluded that the ...