LAUSR

Purpose Cement fly ash gravel (CFG) pile composite foundation is an effective and economic foundation treatment approach, which is significant to build foundation, subgrade construction, and so forth. The purpose of this paper is to present a research on the temperature behaviours of high-latitude and low-altitude island permafrost under CFG pile composite foundation treatment. Design/methodology/approach In the process of CFG pile construction, the temperature of permafrost and pile body was monitored using the temperature sensors. The influence of subgrade height and atmospheric temperature cycle on permafrost temperature was analysed by finite element simulation. Findings In the process of CFG pile construction, the change curve of pile temperature and the temperature of permafrost beside pile following time can be divided into six stages, and the duration of these stages is at least one month. The temperature variation of permafrost while constructing subgrade in FEM has a good agreement with the results of field temperature monitoring. The height of subgrade not only affects the maximum temperature increase of permafrost and the re-frozen time of permafrost after the construction of CFG pile composite foundation, but also affects the temperature variation amplitude of permafrost during atmospheric temperature cycle. Originality/value The research will provide a reference for the design on the CFG pile composite foundation used for island permafrost and guarantee the stability of the structure; thus, it has an important significance.