Laboratory investigations on the mechanical properties degradation of granite under freeze–thaw cycles

To understand the deteriorate characteristics of granite in cold regions, the influences of freeze–thaw cycles on the mechanical properties need to be investigated. The rock specimens (biotite granite from Tibet in China) were frozen and thawed in a temperature and humidity controlled container where the temperature varied from + 40 to − 40 °C and the humidity was kept at 100% continuously. The freeze–thaw tests were conducted for one cycle including 4 h of freezing and 4 h of thawing, and the number of cycles was from 0 to 150. The deterioration of the specimens was examined by the changes of strength, deformation characteristics, elastic modulus, cohesive strength and internal frictional angle in a series of uniaxial and triaxial compression tests. The experimental results show that (1) the axial strain corresponding to the peak stress increases with an increasing of confining pressure and freeze–thaw cycles; (2) The compressive strength decayed exponentially with the number of freeze–thaw cycles, as well as elastic modulus and cohesive strength; (3) the internal frictional angle remained constant in the process of freeze–thaw cycles; (4) The interrelation among compressive strength, confining pressure and number of cycles can be described by Mohr–Coulomb strength criterion. ► The compressive strength, deformation characteristics and elastic modulus are decreased with increasing number of freeze–thaw cycles; ► Several exponential decay function models are proposed to describe their relationships; ► A formulation is proposed to describe the relationship between triaxial compressive strength and the number of freeze–thaw cycles; ► The influence of the number of freeze–thaw cycles on the compressive strength is correctly described by the proposed formulation.