Abstract:

In order to investigate the creep behavior of hightemperature and high ice-rich frozen soils, a series of pressure tests were carried out in permafrost regions on the Qinghai-Tibetan Plateau. The test results showed that it was acceptable to describe the pressure creep curve employing the engineering theory of creep proposed by Ladanyi. The average proportion of instantaneous elastic strain in the total strain under each pressure in every test was in the range of 3% to 7%. Even a slight change in temperature could cause great change of the shear modulus of warm permafrost. The primary creep strain could be calculated using a power function with the strengthening factor k=1.87 and the strain coefficient had a positive linear relationship with the absolute value of the temperature. The relationship between steady creep rate and pressure could be expressed in the Glen creep model. The parameter n increased linearly with increasing volumetric ice content and the parameter n equaled 3.85 when the volumetric ice content reached 100%, which was a little different from the results of laboratory experiments proposed by other researchers. At low temperature, the creep rate was relatively small and when the temperaute approximate to the zero degree, the creep rate increased rapidly.

Key words: Qinghai-Tibetan Plateau, pressure test, permafrost, creep, Glen creep model