The comprehensive understanding of freeze-thaw (F-T) deterioration and deformation properties of rock is a critical basis for frost damage prevention on cold regional rock engineering. In freezing process, plastic strain generates in rock when the stress induced by pore ice pressure (PIP) becomes higher than yield strength, and unrecoverable deformation accumulates in rock under multiple F-T cycles. Therefore, this study presents a thermal-mechanical modelling on cumulative F-T deformation of rock under cyclic F-T action. In the modelling of mechanical action, the microporomechanics theory is applied with a spherical element model in the derivation of equilibrium equations of rock, and the Drucker-Prager criterion is utilized with dilatancy effect of rock considered to describe unrecoverable plastic deformation cumulated in rock under multiple F-T cycles. The thermal process is modelled with unfrozen water content and latent heat accounted. The proposed thermal-mechanical modelling method is validated based on experiments and numerical simulations of F-T deformation of sandstone, and it is able to simulate the temperature and F-T deformation of rock in acceptable precision. The numerical distributions of temperature, PIP, maximum principal strain and displacement are exhibited and show that the plastic region begins to develop in rock matrix with PIP exceeding the elastoplastic critical pressure when temperature drops to about −2 °C and grows rapidly when temperature drops from −2 to −6 °C. Several F-T cycles later, large unrecoverable plastic strain remains in sandstone though PIP dissipates after thawing. The cumulative F-T deformation, porosity increment and maximum of plastic volume ratio are much greater under condition with freezing temperature of −20 °C, compared with condition −10 °C. Besides, as cycle number increases, the plastic volume ratio becomes smaller and its decrease rate attenuates.

中文翻译：

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基于考虑剪胀性的Drucker-Prager准则的弹塑性多孔岩石累积冻融变形热力建模


全面认识岩石的冻融劣化和变形特性是寒区岩石工程冻害防治的重要基础。在冻结过程中，当孔隙冰压力（PIP）引起的应力高于屈服强度时，岩石中会产生塑性应变，并且在多次F-T循环下，岩石中会积累不可恢复的变形。因此，本研究提出了循环 F-T 作用下岩石累积 F-T 变形的热力模型。在力学作用建模中，应用微孔隙力学理论和球形单元模型推导岩石平衡方程，并利用考虑岩石剪胀效应的Drucker-Prager准则来描述岩石在多次作用下累积的不可恢复的塑性变形。 F-T 循环。热过程通过未冻结的水含量和潜热进行建模。所提出的热力模拟方法基于砂岩F-T变形的实验和数值模拟进行了验证，能够以可接受的精度模拟岩石的温度和F-T变形。温度、PIP、最大主应变和位移的数值分布显示，当温度降至 -2 °C 左右时，岩石基质中塑性区域开始发展，PIP 超过弹塑性临界压力，并且当温度降至 -2 °C 左右时，塑性区域迅速增长。 −2 至 −6°C。几个 F-T 循环后，尽管 PIP 在解冻后消散，但砂岩中仍然存在大量不可恢复的塑性应变。 冷冻温度-20℃条件下的累积F-T变形、孔隙率增量和最大塑性体积比均较-10℃条件下大得多。此外，随着循环次数的增加，塑性体积比变小，其下降幅度减弱。