Uniaxial compressive mechanical properties of rock at low temperature

Based on the nonlinear thermo-elastic theory,a constitutive equation with variable properties was established in consideration of the expansion force of pore ice,and the relationships of the uniaxial compressive strength and the mechanical parameters with temperature were proposed in the drying and low-temperature condition and the saturated freezing condition.Mechanical properties of granite under uniaxial compression were discussed according to compression experimental results of granite in both the conditions.It is shown that the compressive strength under the saturated freezing condition is greater than that under the condition of drying and low temperature,and their difference increases with decreasing temperature.The compressive strength in the same state increases with decreasing temperature,and the growth rate gradually decreases.The additional strength is mainly caused by thermal effects of the rock matrix,and the expansion force of pore ice has relatively little effect.The elastic modulus of granite increases with decreasing temperature in both the conditions,but the change of Poisson's ratio is little.