冻融循环作用下损伤砂岩物理特性研究

岩体破坏是其内部损伤积累发展的结果,在季节性温度变化作用下,岩体劣化程度加剧,使得寒区工程岩体发生失稳的概率大大增加。因此有必要对损伤岩样在周期性冻融作用下的劣化规律进行研究。本文在理论分析的基础上,对冻融过程中预加载损伤和无加载损伤的砂岩岩样,每次冻结、融化、低温烘干后各个岩样的纵波波速、电阻率这两个物理参数进行了测量,尤其还对岩样的电阻率进行了测定,并对这两个物理参数进行劣化度分析,结果表明:岩样的纵波波速与冻融循环周期呈二次函数关系,电阻率与冻融循环周期呈对数关系,且这两个物理参数对岩样的影响次序为:电阻率纵波波速。这就说明电阻率这个评价指标对岩样物理特性较为敏感,为工程评价寒区岩石的稳定性提供参考。

Physical characteristics of sandstone under freeze-thaw cycles

Rock mass failure is a result of internal damage accumulation and development, and it is exacerbated in the condition of seasonal temperature change because the enhanced strength degradation of rock mass in cold regions causes a great increase in the probability of rock mass instability. Hence, it is necessary to study the cyclic freeze-thaw deterioration of damaged rock. This paper describes an experiment of sandstone samples in the conditions of preload damage as well as no load damage in the freeze-thaw process. For the specimens that had experienced freezing, thawing, and drying at low temperature, we measured their longitudinal wave celerity and rock resistivity and analyzed the degradation degree of these two parameters. Results show a quadratic relationship of the celerity versus the number of freeze-thaw cycles and a logarithmic relationship of the resistivity versus the cycle number. And in the same testing conditions, the changes in the resistivity are greater than those in the celerity. This means that resistivity is an evaluation index more sensitive to rock physical properties and it is a useful index for evaluation of the stability of rock structures in cold regions.