中文摘要：

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。

英文摘要：

The thermal effects of rock in long-term varying low-temperature environment are mainly expressed by the mechanical parameters,thermal coefficients of rock and the pore ice expansion coefficient in the saturation state changing with the decreasing temperature.These changes have some significant influences on the deformation and strength characteristics of rock.The constitutive equation considering the thermal effects and the ice expansion coefficient is established according to the nonlinear thermo-elastic theory of varying properties,and the changing relationships of the thermal coefficients with temperature and their determining method are given under the uniaxial compressive condition.Then,the relationships of the thermal effects with low temperature for granite are obtained by means of the uniaxial compression test results of granite under the different dry low temperatures and the saturated frozen,and the influence of the different conditions on the compressive strength characteristics of granite is discussed.The analysis results show that the thermal coefficient and the ice expansion coefficient of granite decrease gradually with the increasing of the relative temperature difference under the varying low-temperature environment,and the reducing rate of thermal coefficient is lower than that of the ice expansion coefficient.The coefficient of the thermal expansion is greater than that of the ice expansion under the same temperature difference.The thermal stress and the ice expansion stress increase with the low temperature nonlinearly.The compressive strength values of granite in the two states are both increasing;but the thermal stress is the dominating,and the axial stress increment caused by the thermal coefficient is always larger than that caused by the ice expansion force.The proposed method and the obtained results can be supplied for the research on material deformation properties and engineering application under long-term varying low temperatures.