冻土蠕变指标试验研究

通过不同温度、不同加载应力作用下冻结兰州黄土、黏土、砂质黏土的蠕变试验，分析了蠕变曲线、初始应变、流变起始应变与流变起始时间、破坏应变与破坏时间及相对蠕变指标.结果表明：3种土质冻土的蠕变曲线变化规律大致相同，加载过程中，应变非线性增加，且加载应力越大、温度越高，初始应变越大；流变起始时间与破坏时间都与加载应力、温度有密切关系，加载应力越大、温度越高，越先出现流变和破坏. 对于相同的土质，加载应力和温度对流变起始应变、破坏应变的影响不大；对于不同土质的初始应变、流变起始应变和破坏应变，都是黏土最大、砂质黏土次之、兰州黄土最小. 3种土质冻土的初始加载段和非稳定蠕变段所占的时间较短，但产生的应变却较大；同时，温度越高，相对流变时间越短、相对破坏时间越长，说明非稳定蠕变阶段所占的时间随温度的升高而变短、稳定蠕变阶段所占的时间随温度的升高而变长.

Experimental study of the creep indexes of frozen soil

The creep characteristics of frozen Lanzhou loess, clay and sandy silt in different temperatures and loadings were studied experimentally, and then the creep curves were analyzed, including rheological initial strain, rheological start time, failure strain, failure time and relative creep indexes. It is found that the creep curves of the three kinds of soils are roughly similar each other, showing a nonlinear strain increasing in the process of loading and initial strain increasing with increase in temperature and loading. The rheological start time and failure time are close relation with temperature and loading, rheological time and failure time appear earlier under higher temperature and greater loading. For the same kind of soil, the initial strain and temperature have little impact on the rheological initial strain and failure strain. For different kinds of soil, the initial strain, rheological initial strain and failure strain of clay are the maximum, followed by sandy silt and Lanzhou loess. The initial loading period and unsteady creep stage of the three kinds of frozen soil are short, but the strain is larger, the relative creep time is shorter and relative failure time is longer under higher temperature at the same time. It is also revealed that the unsteady creep stage is shorter and the steady creep stage increases with temperature increasing.