考虑温度效应的层状复合岩石力学损伤试验及模型研究

MECHANICAL DAMAGE TEST AND MODEL STUDY OF LAYERED COMPOSITE ROCK CONSIDERING TEMPERATURE EFFECT

  • 摘要: 为研究层状复合岩石高温作用下的力学特性,对相似材料制备的层状复合岩石进行20℃(室温),100℃,200℃和300℃热处理,并开展单轴压缩试验获取其物理力学参数。结果表明,随着温度升高,层状复合岩石质量变化率与体积膨胀率呈上升趋势,且在100℃时增幅明显。拟合各力学参数的经验公式发现,峰值强度及弹性模量趋于劣化并呈线性降低,峰值应变与温度成正相关。随着温度升高,层状复合岩石呈剪切–滑移型破坏,单一类岩石由剪切破坏向张拉–剪切破坏转化,破坏时微裂纹数量增多,在300℃时延性特征显著。引入考虑温度效应的岩石本构模型并拟合了不同温度下的应力应变曲线,该模型较好地表征了热处理后层状复合岩石的损伤演化规律及破坏特征,合理地揭示了层状复合岩石高温作用后的损伤机理。

     

    Abstract: In order to study the mechanical characteristics of layered composite rocks under high temperature, the layered composite rocks prepared by similar materials were heat treated at 20°C (room temperature), 100°C, 200°C and 300°C, and the physical and mechanical parameters were obtained by uniaxial compression tests. The results show that the mass change rate and volume expansion rate of the layered composite rock present an upward trend with the increase of temperature, and the growth is obvious at 100°C. It is found that the peak strength and elastic modulus tend to deteriorate and decrease linearly, and the peak strain is positively correlated with temperature by fitting the empirical formula of various mechanical parameters. With the increase of temperature, the layered composite rocks show shear-slip failure, and the single type rocks transform from shear failure to tension-shear failure. The number of microcracks grows during failure, and the ductility characteristics are significant at 300°C. A constitutive model of rock considering temperature effect is introduced and the stress-strain curves at different temperatures are fitted. The model can well characterize the damage evolution law and failure characteristics of layered composite rock after heat treatment, and reasonably reveal the damage mechanism of layered composite rock after high temperature.

     

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