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冻融环境中温度是岩石性态变化的关键影响指标之一,而冻融试验中岩石的热量传递和温度变化规律国内和国际都未形成统一认识。为探究岩石在冻融环境中的热量传递和温度变化规律,利用室内试验和数值计算方法分别研究冻结和融化过程中试样温度平衡的过程和时程规律。利用3种岩石进行饱和态的冻融循环试验,试样中心温度监测表明,冻结和融化过程的试样温度均存在显著的3段式变化特征,其中相变过程是一个较为特殊和重要的阶段,相变温度均在0℃~-1℃范围。随着试验温度区间增大,冻结和融化各阶段时长显现出不同规律,冻结过程总时间逐渐降低,而融化过程总时间先降低后升高。基于第3类热传导边界条件,利用Comsol Multiphysics有限元数值计算平台,分析考虑相变阶段的冻结和融化过程,数值计算结果与试验结果吻合较好。数值计算结果显示,试样不同位置的冻结与融化特征主要体现在相变阶段差异,而试样孔隙率对该阶段的影响最大,剩余温度势造成对称温度区间和非对称温度区间的冻结、融化特征的显著差异。
The temperature in the freeze-thaw environment is one of the key influence indicators of the change of rock properties. However, the law of heat transfer and temperature change of rock in the freeze-thaw test does not form a unified understanding both domestically and internationally. In order to explore the law of heat transfer and temperature change of rock in freezing and thawing environment, the temperature balance process and the time history of the sample during freezing and thawing were studied respectively by means of in-house test and numerical calculation. Three types of rock were used to test the saturated-state freeze-thaw cycle. The monitoring of the sample center temperature showed that there were significant three-stage variations in the sample temperature during the freezing and thawing process. Phase transition was a special and important stage , The phase transition temperature is in the range of 0 ℃ ~ -1 ℃. As the experimental temperature range increases, the duration of the freezing and thawing phases shows different laws, the total time of the freezing process gradually decreases, and the total time of the melting process first decreases and then increases. Based on the third type of heat conduction boundary conditions, the Comsol Multiphysics finite element numerical calculation platform was used to analyze the freezing and thawing process considering the phase transition. The numerical results agree well with the experimental results. The numerical results show that the freezing and thawing characteristics at different positions of the sample are mainly reflected in the phase transition phase difference, while the porosity of the sample has the greatest impact on this phase. The residual temperature potential causes the freezing and thawing in the symmetrical temperature range and the non-symmetrical temperature range Significant differences in characteristics.