Experimental Study On Compression Deformation Of Frozen Soil In Near Phase Transition Zone

With the global warming,the annual mean temperature of Qinghai Tibet Plateau is increasing,which brings many new problems and challenges to the lifeline engineering facilities such as roads,railways and pipelines in permafrost region of near phase transition region,especially the permafrost regions near the phase change area have high unfrozen water content,resulting in very special physical and mechanical properties.Under the effect of additional stress,the migration law of unfrozen water and how the pore water pressure change are the problems to be solved.At the same time,it plays an important role in identifying the deformation mechanism of frozen soil in the near phase transition zone.`In order to verify consolidation existing consolidation effect in permafrost deformation,this paper carried out a laboratory test primarily,designed a sensor to measure the pore water pressure,and tested the connectivity of the unfrozen water inside the frozen soil in near the phase change zone.The results show that when the temperature is higher than-1 ?,the unfrozen water in frozen soil is connectivity.The unfrozen water in the frozen soil will migrate under the load,the unfrozen,that is,the unfrozen water with high pore water pressure will migrate to low pore pressure along the percolation channel.In order to further obtain the consolidation degree of frozen soil under the load,the pore water pressure curve of frozen soil under different conditions is analyzed,and concluded that temperature,drainage condition and external load have different effects on pore water pressure of frozen soil in near transformation region and analyzed the cause of the effect in theoretical aspects later.The results of this study will provide some basic data for the design and construction engineering of the Qinghai Tibet area,and have a certain reference value for the study of theories properties of the high temperature frozen soil.