Research on dynamic variation of moisture，temperature and deformation of cone-cylindrical pile under freeze-thaw cycles
SHI Xiangyang1，2，ZHANG Ze1，LI Dongqing1，ZHOU Panfeng3，FENG Wenjie1
(1. State Key Laboratory of Frozen Soil Engineering，Northwest Institute of Eco-environment and Resources，Chinese Academy of Sciences，Lanzhou，Gansu 730000，China；2. University of Chinese Academy of Sciences，Beijing 100049，China；
3. Guangzhou Academy of Nuclear Engineering Investigation，Guangzhou，Guangdong 510800，China)
Abstract：In cold regions，the moisture，temperature and deformation of foundations is affected by freeze-thaw cycles. The cone-cylindrical pile is a kind of short expanded pile with a base，which has been widely used in permafrost regions，but its theoretical research is still lagging behind engineering practice. Through model test，temperature field，moisture field and vertical deformation of pile and soil were monitored by temperature sensors，moisture sensors and laser displacement meters, respectively. Combined with the number of freeze-thaw cycles，the dynamic variation laws of moisture，temperature and deformation were analyzed. The results show that the freezing depth of backfill increases with freeze-thaw cycles. The pile foundation is more sensitive to the ambient temperature change and thermal conductivity of pile is better than that of soil，so pile foundation can provide a good heat exchange channel between deep soil and external environment. Therefore，the temperature field distribution during the freeze-thaw cycles is closely related to the pile shape. The moisture migration is driven by temperature potential，gravity potential and capillary action，and the migrating water is blocked by frozen layer and the base of pile. The water content reduces at pile side，and accumulates at the pile bottom. The deformation of pile and soil increases with the freeze-thaw cycles. The maximum deformation of pile foundation is 8.0 mm，and the soil deformation is up to 1.9 mm. The relative deformation between pile and soil dramatically increases in the first several cycles，and then increases slowly，ultimately achieves a dynamic stable deformation stage.
史向阳1，2，张 泽1，李东庆1，周攀峰3，冯文杰1. 冻融循环作用下锥柱式桩基础水热及变形动态变化规律研究[J]. 岩石力学与工程学报, 2019, 38(S1): 3092-3101.
SHI Xiangyang1，2，ZHANG Ze1，LI Dongqing1，ZHOU Panfeng3，FENG Wenjie1. Research on dynamic variation of moisture，temperature and deformation of cone-cylindrical pile under freeze-thaw cycles. , 2019, 38(S1): 3092-3101.
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2019, Vol. 38 
