Mechanical behavior of salt rock under uniaxial compression and creep tests

Abstract

The mechanical characteristics of salt rock are investigated using uniaxial compression tests and creep tests in a salt diapir located in the south of Iran. To investigate how the microstructure evolution of salt rock due to creep test affects the stress-strain behavior, the crept samples were again tested at a constant displacement rate. The test results showed that the axial peak stress, axial peak strain, and modulus of elasticity gradually increase with increasing strain rate. The stress-strain curves were typical for a ductile material characterized by moderate strain hardening. The creep strain and creep rate increased with increasing axial stress. The Burgers viscoelastic creep model agreed quite well with the experimental creep data. The microstructure observations indicated that grain-boundary cracking and grain boundary sliding were the dominant deformation mechanisms. Under the uniaxial compression test, the crept samples showed a slightly higher modulus of elasticity compared to the intact salt samples. Finally, it seems that free dislocations increased during the creep test led to strain hardening of salt samples through the uniaxial compression test.