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寒区岩石在季节性温度变化下会经历冻胀融缩过程,研究低温岩石中未冻水含量以及冻胀变形规律是进行寒区工程数值仿真和稳定性分析的关键问题。岩石是不同于土体的脆性多孔介质材料,孔隙中的未冻水含量还无法通过实验直接测量;基于累计孔隙体积分布规律,考虑孔隙水的冻结点变化和未冻水膜的影响建立低温岩石未冻水含量理论表达式,实例证明该计算式具有较高的可靠度。假定岩石为弹性孔隙介质,基于孔隙冰与岩石孔隙间的膨胀耦合关系可计算冰压力;利用应变等价原理将孔隙中的冰压力等效为岩石表面的三向拉应力,从而根据弹性理论建立了有效冻胀力下低温饱和岩石冻胀变形模型。结果表明饱和岩石低温冻胀变形与岩石基质的力学参数、岩石孔隙率以及未冻水含量等因素有关。最后通过与2个已有的室内冻胀变形实验对比,说明本文冻胀变形模型的正确性以及实用性。
The rock in cold area will experience the process of frost heaving and thawing under the seasonal temperature change. Studying the unfrozen water content and frost heave deformation in low temperature rock is the key issue for numerical simulation and stability analysis of cold area engineering. Rock is a brittle porous medium which is different from the soil. The unfrozen water content in the pores can not be directly measured by experiments. Based on the cumulative pore volume distribution, considering the change of freezing point of pore water and the influence of unfrozen water film, The theoretical expression of unfrozen water content shows that the calculation formula has high reliability. Assuming that the rock is an elastic pore medium, ice pressure can be calculated based on the expansion coupling relationship between pore water and rock porosity. Using the strain equivalence principle, the ice pressure in the pore is equivalent to the three-direction tensile stress on the rock surface, so that the elastic theory is established Frost heaving deformation model of low temperature saturated rock under effective frost heave force. The results show that the deformation of saturated rock at low temperature is related to the mechanical parameters of rock matrix, rock porosity and unfrozen water content. At last, the correctness and practicability of the frost heave deformation model in this paper are illustrated through comparison with two existing indoor frost heave deformation experiments.