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长期处于变低温环境中的岩石热力学效应主要表现为材料的力学特性参数、热力系数和饱和冻结状态孔隙冰胀系数等随温度改变而发生变化,这种变化对岩体的变形及强度特性均有显著影响。根据变物性参数的非线性热弹性理论,建立了考虑热力系数和冰胀力系数的本构方程,给出了单轴压缩条件下热力效应系数随温度变化的分析格式和确定方法;借助于花岗岩不同低温干燥和饱和冻结状态的单轴压缩试验资料,获得了花岗岩低温热力效应与温度的关系,并探讨了其对花岗岩抗压强度的影响特性。分析表明,在变低温环境下花岗岩热力系数和冰胀力系数均随相对温差的增大而逐渐减小,热力系数降低速率小于冰胀系数降低速率,在同一温差下热力系数大于冰胀系数;热应力和冰胀应力与温度改变量呈非线性增长关系;花岗岩抗压强度在两种状态下均呈增大趋势,但主要以热应力为主,热力系数引起的试样轴向应力增量总是大于冰胀力引起的轴向应力增量。所给方法及研究成果可用于长期处于变低温状态下材料的力学性能研究及其工程应用。
Long-term low-temperature environment in the rock thermodynamic effects mainly for the mechanical properties of the material parameters, thermal coefficient and saturated frozen state pore expansion coefficient changes with the temperature changes, this change on the rock deformation and strength characteristics have Significantly affected. According to the nonlinear thermoelastic theory of variable physical parameters, the constitutive equation considering the coefficient of thermal coefficient and the coefficient of ice expansion force is established. The analysis format and determination method of the coefficient of thermal effect with temperature under uniaxial compression are given. By means of granite Uniaxial compression test data of different low-temperature drying and saturated freezing conditions were used to obtain the relationship between the thermal effect of low-temperature granite and temperature. The effect of granite on the compressive strength of granite was also discussed. The analysis shows that both the thermal coefficient and the ice expansion coefficient of granite decrease with the increase of relative temperature difference at low temperature, the rate of decrease of thermal coefficient is lower than the rate of decrease of ice expansion coefficient, and the coefficient of thermal expansion is larger than that of ice expansion coefficient at the same temperature difference. The compressive strength of granite shows an increasing trend under both conditions, but mainly the thermal stress, and the axial stress increment of the sample caused by the thermal coefficient Always greater than the axial stress increment caused by ice-swell force. The given methods and research results can be used to study the mechanical properties and engineering applications of materials under long-term low temperature.