高温-高含冰量冻土原位旁压蠕变试验

In-Situ Pressuremeter Creep Test on High-Temperature and High Ice-Rich Permafrost

为了研究高温-高含冰量冻土的蠕变特性，在青藏高原多年冻土区开展了旁压蠕变试验。试验结果表明：旁压蠕变曲线可以借鉴Ladanyi的工程蠕变理论来表示；每个试验中瞬时弹性应变在各级压力下的总应变中所占比例的平均值为3％～7％，冻土温度轻微的改变都会引起剪切模量的大幅变化；冻土的初始蠕变应变可以采用幂函数形式来计算，其强化系数k=1．87，应变系数与负温绝对值之间呈线性正相关关系。稳定蠕变阶段的应变速率可以用Glen蠕变模型来表示，其中参数”随体积含冰量的增加而线性增加；若体积含冰量外推至100％（纯冰）时，n=3．85，这与前人通过室内试验得出的结果有些差异。温度较低时．蠕变速率较小；当温度趋近于0℃时，蠕变速率迅速增大。

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.