Abstract
The permafrost in wetland area is very sensitive to temperature change due to its special geological conditions. By observing the temperature data of the pile-soil junction of the bored concrete pile, as well as measuring the geotechnical parameters and thermophysical parameters of the soil around the pile, it statistically analyzes the significant correlation factors related to the time when the temperature of the pile-soil junction rises to the peak, including the dry density and liquid index of the frozen soil. The formula for calculating peak time is summarized and the fitting effect is compared. The results show that peak time is positively correlated with dry density and obeys cubic curve. It is negatively correlated with the liquid index and follows the growth function curve. The peak time was not significantly correlated with the buried depth of the temperature sensor, peak temperature corresponding to the peak time, natural ground temperature, original temperature of pile wall, soil thermal conductivity, volume heat capacity, natural moisture content and plasticity index of frozen soil. The influence of concrete ratio on peak time is significant, and its correction coefficient follows S-shaped curve.
Highlights
With the global warming, the permafrost problem in cold regions is attracting more and more international attention
From this study the following conclusions are drawn: (1) When the hydration heat generated by concrete pile foundation is transferred in frozen soil, its peak time is significantly correlated with the dry density of frozen soil, which increases with the increase of dry density
(2) When the hydration heat generated by concrete pile foundation is transferred in frozen soil, its peak time is significantly related to the liquid index of frozen soil, which decreases with the increase of the liquid index
Summary
The permafrost problem in cold regions is attracting more and more international attention. Permafrost soils contain enormous amounts of organic carbon, which could act as a positive feedback to global climate change [6,7,8]. The temperature sensitivity of decomposition of the enormous global stocks of soil organic matter has recently received considerable interest. Wetlands, peatlands and permafrost soils generally have higher carbon densities than upland soil minerals [8]. Permafrost soils and a large fraction of peatland soils occur at high latitudes, where warming is expected to be greatest, and, has already begun [9,10]. Even small permafrost temperature changes and anthropogenic thermal disturbances can have a significant impact on carbon sink storage and migration.
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