Study on the freezing-thawing deformation of consolidated soils under high pressure

摘要

The freezing-thawing deformation behaviors of consolidated soils under high pressure have been investigated in a high-pressure-low-temperature (HPLT) K0 consolidation apparatus with a small strain sensor.The tests cover a variety of frozen soil temperatures ranging from-2 ℃ to-10 ℃,and a series of applied pressures ranging from 1 MPa to 5 MPa.The test results show that,for the consolidated soils under high pressure,their freezing-thawing deformation was caused by the realignment and the deformation of soil particles,the phase change of water,and the water redistribution in the soil.As for the deformation produced by thermal expansion and contraction,it is about 0.04～0.05 mm,accounting for only about 7％～9％ of the total deformation.Taking the freezing-thawing deformation produced by temperature disturbance as a creep deformation,the creep models of the developing soil deformation will be determined by the soil's final temperature,i.e.,the desired temperature.For the soils under a desired temperature between-2 ℃ and-5 ℃,the freezing-thawing deformation develops according to a non-attenuation creep model;but for the soils with a desired temperature lower than -5 ℃,a full attenuation creep model is followed.The applied pressure and soil type also have a significant influence on the maximum freezing deformation.Generally,the greater the desired pressure applied,the less the maximum deformation is;and the loess freezing deformation is larger than that of sand.