伊明,赵涛,马飞飞,等. 基于Weibull分布的冻结砂岩损伤本构模型研究[J]. 煤田地质与勘探,2022,50(8):116−124. DOI: 10.12363/issn.1001-1986.22.02.0070
引用本文: 伊明,赵涛,马飞飞,等. 基于Weibull分布的冻结砂岩损伤本构模型研究[J]. 煤田地质与勘探,2022,50(8):116−124. DOI: 10.12363/issn.1001-1986.22.02.0070
YI Ming,ZHAO Tao,MA Feifei,et al. Study of constitutive model of frozen sandstone damage based on Weibull distribution[J]. Coal Geology & Exploration,2022,50(8):116−124. DOI: 10.12363/issn.1001-1986.22.02.0070
Citation: YI Ming,ZHAO Tao,MA Feifei,et al. Study of constitutive model of frozen sandstone damage based on Weibull distribution[J]. Coal Geology & Exploration,2022,50(8):116−124. DOI: 10.12363/issn.1001-1986.22.02.0070

基于Weibull分布的冻结砂岩损伤本构模型研究

Study of constitutive model of frozen sandstone damage based on Weibull distribution

  • 摘要: 冻结岩石的变形破坏特性是冻结法施工过程中的基础力学问题,在荷载作用下不同冻结温度岩石的力学特性和变形特征差异性较大,严重影响冻结壁的安全与稳定。因此,研究冻结岩石的损伤本构关系,对指导冻结法设计与施工具有重要意义。为分析荷载作用下冻结岩石变形破坏的全过程,采用Weibull分布描述岩石材料的非均质性,基于Drucker-Prager破坏准则,建立三轴应力状态下岩石损伤本构模型,结合冻结砂岩三轴压缩试验,重点分析本构关系中均质度系数m、平均强度F0与冻结温度和围压的变化关系,对损伤本构方程进行修正,并基于此模型研究冻结砂岩的损伤演化规律。结果表明:在相同围压下,随着冻结温度的降低,砂岩峰值强度显著增大,峰值应变减小,压密阶段逐渐减弱,弹性变形阶段斜率增加,岩石脆性破坏特征明显。在相同冻结温度下,均质度系数m和平均强度F0随围压升高无显著变化,而随着冻结温度的降低,mF0分别呈现指数增长和线性增长,说明随着冻结温度的降低,砂岩冻结越充分,内部自由水冻结成冰占比及冰体强度增长幅度越大,尤其在0~–10℃内提升效果显著,冻结作用提高了砂岩的均质性和平均强度。基于不同冻结温度砂岩的力学特性和变形规律,对不同冻结温度砂岩的损伤本构方程进行了修正。依据修正本构模型研究发现,损伤演化曲线能够很好地反映冻结砂岩压缩试验的压密、线弹性、屈服变形及应变软化各阶段的变形特征,验证了模型的合理性。研究结果为低温环境下岩石力学特性研究及地下冻结工程设计施工提供有益的参考。

     

    Abstract: Abstract: The deformation and destruction characteristics of frozen rock is a basic mechanical problem encountered during the construction using the freezing method. Under the action of load, the mechanical characteristics and deformation characteristics are greatly different for the rock with different freezing temperatures, which significantly affects the safety and stability of the freezing wall. Therefore, the study of the damage constitutive relation of the frozen rock is significant for instructing the freezing method design and construction. In order to analyze the whole process of the frozen rock deformation and destruction under load action, the Weibull distribution was adopted to describe the heterogeneity of rock materials. On the basis of the Drucker-Prager destruction principle, the rock damage constitutive model under triaxial stress state was established. In combination of the triaxial compression test of freezing sandstone, the change relations among the homogeneity coefficient m, average strength F0 and the freezing temperature as well as peripheral pressure in the constitutive relation were focused on in the analysis; the damage constitutive equation was corrected, and the damage evolution regularity of the frozen sandstone was studied based on this model. As indicated by the study, according to the monoaxial and triaxial compression tests of the frozen sandstone, under the same peripheral pressure, as the freezing temperature drops, the sandstone strength peak was significantly increased; the strain peak was reduced; the strength was decreased at the compaction stage; the slope was increased at the elastic deformation stage. The brittle destruction characteristics of the rock were significant. Under the same freezing temperature, there was no significant change in homogeneity coefficient m and average strength F0 with the rising peripheral pressure. However, with the decreased freezing temperature, m and F0 showed exponential growth and linear growth respectively. Accordingly, as the freezing temperature dropped, the sandstone was frozen better, and both the ratio of the ice formed in the internal free water and the ice strength enhancement were higher, which was especially significant in 0 to −10℃. The freezing effect increased the homogeneity and average strength of sandstone. The damage constitutive equation of the sandstone with different freezing temperatures was corrected based on the mechanical characteristics and deformation regularity of the sandstone with different freezing temperatures. On the basis of the corrected constitutive model study, the damage evolution curves can well reflect the compaction, linear elasticity, yield deformation and deformation characteristics of each stage of the strain softening in the frozen sandstone compression test, verifying the rationality of the model. The study result provided useful reference for the rock-mechanics characteristic study under low-temperature environment and the underground freezing engineering design and construction.

     

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