考虑岩石微元强度呈对数正态分布的冻融岩石损伤特性

冻融环境下准脆性岩石损伤力学特性对寒区工程建设有重要影响。由于准脆性岩石存在特征长度，其尺度效应不再符合Weibull尺度效应统计理论。本文以准脆性岩石为研究对象，考虑准脆性岩石微单元强度服从对数正态分布的条件下，依据D-P破坏准则，运用损伤力学理论建立了围压作用下冻融准脆性岩石的损伤本构模型，对冻融准脆性岩石损伤力学特性进行了探讨。研究表明，（1）采用对数正态分布建立的冻融准脆性岩石损伤力学本构模型与试验结果一致，该模型反映出冻融环境下准脆性岩石总损伤沿应变、围压和冻融循环路径相互作用，能够揭示出准脆性岩石损伤演化的本质特征。（2）冻融与围压共同作用下，准脆性岩石应力-应变变化关系可划分为线弹性阶段、非线性强化阶段、应力减弱阶段以及应变衰退阶段。（3）当准脆性岩石所受围压一定时，冻融次数是使准脆性岩石冻融受荷总损伤增大的关键因素。冻融循环次数对准脆性岩石的损伤劣化起促进作用；当准脆性岩石所受冻融循环次数不变时，冻融受荷总损伤随围压增大而减小，即围压对准脆性岩石力学性能劣化起抑制作用。相关研究成果对寒区岩体工程安全稳定性评价有一定的理论参考价值。

Damage characteristics of freezing-thawing rock with lognormal distribution of microelement strength are considered

The mechanical properties of quasi-brittle rocks damage in freeze-thaw environments have important implications for engineering construction in cold regions.Due to the presence of characteristic lengths in quasi-brittle rocks, its scale effects no longer conform to the statistical theory of Weibull scale effects.The article takes quasi-brittle rocks as the research object, based on the micro-unit strength of quasi-brittle rocks obeying a log-normal distribution, based on the D-P damage criterion, the damage mechanics theory is used to establish the intrinsic damage model of freeze-thaw quasi-brittle rocks under the action of surrounding pressure, and the damage characteristics of freeze-thaw quasi-brittle rocks are discussed.This research shows:(1) The constitutive damage model of quasi brittle rocks based on lognormal distribution is consistent with the experimental results.The model reflects the interaction of total damage of quasi brittle rocks along strain, confining pressure and freeze-thaw cycle path under a freeze-thaw environment, and can reveal the essential characteristics of damage evolution of quasi brittle rocks. (2) The stress-strain relationship of quasi brittle rocks under freeze-thaw and confining pressure can be divided into linear elastic stage, nonlinear strengthening stage, stress weakening stage and strain decline stage. (3) When the confining pressure of quasi brittle rocks is constant, the number of freezing and thawing is the key factor to increase the total damage of quasi brittle rocks.The number of cycles of freeze-thaw is a factor for promoting the damage degradation of brittle rocks.When the number of cycles of freeze-thaw is constant, the total damage of frozen thaw load decreases with the increase of confining pressure, that is, the deterioration of mechanical properties of the quasi brittle rocks under confining pressure plays a role in inhibiting the deterioration of mechanical properties.The research of this paper has a certain role in promoting the theoretical analysis of the safety and stability of rock mass engineering in cold regions.