高温冻土松弛特性试验研究

Experimental study of relaxation characteristics of warm permafrost

为深入认识高温冻土的松弛规律,查明预应变对松弛过程的影响,开展了一系列室内高温冻土松弛试验。研究发现,预应变过程明显影响了高温冻土的松弛过程,表现为预应变量增大,瞬时松弛量相应提高,松弛稳定历时延长;对于恒应变速率加载而言,恒应变速率增大延长了松弛稳定历时,并提高了高温冻土的松弛速率;对于恒应力率加载过程而言,恒应力率增大,松弛稳定历时延长,松弛速率也随之提高。偏应力与时间对数的关系具有明显的非线性特征,不能简单描述为单一直线,采用双曲线型关系描述其关系时效果很好,根据双曲线型获得了一种经验型的流变关系,并对该流变关系的可靠性进行了验证。

To get a better understanding of relaxation process of warm permafrost and find factors influencing on this process,a series of laboratory triaxial relaxation tests are conducted.The results indicate that the instantaneous relaxation increases with pre-strain and the relaxation stabilization duration prolongs.For the constant strain rate loading,the increase in strain rate leads to bigger relaxation rate and longer stabilization duration.For constant stress rate loading,the stress rate iucreases,the stabilization prolongs and the relaxation rate increases.The relationship between deviatoric stress and time cannot be simply described by linear relation but shows a obvious non-linear tendency.However,the relation between deviatoric stress and time can be simulated by a hyperbolic relation,and based on this relation,a new empirical rheological relation is obtained and the reliability of the rheological relation is verified by the validation results.