Due to various factors, high-temperature rocks are often affected by different cooling methods. They will lead to changes in rock mechanical properties, which firmly connect with the safety and stability of practical projects. At present, there are many studies of the microscopic characteristics of rocks under different cooling methods, but few on the mechanical characteristics of rocks under the same conditions. Therefore, it is necessary to carry out experimental research on the mechanical properties of rock under different cooling methods. The study shows that the deterioration degree of the sample increases gradually with temperature rising and the cooling methods have different effects on the change of the sample in mass, volume and density. The stress–strain curve of the sample is divided into the crack compaction stage, elastic deformation stage, nonlinear deformation stage and failure stage. The peak strength of the naturally cooled sample is higher than that of the water cooled. The peak strength comes with a trend that goes up first, and then down with the temperature increasing. The uniaxial compression failure of the sample under uniaxial action is tensile failure. The failure characteristic of the sample is influenced both by the cooling modes and the temperature.
Underground rock engineering often encounters long-term cyclic loading and unloading. Under the influence of this effect, the mechanical characteristics of rocks will inevitably change, which will affect the stability and safety of underground engineering. Therefore, it is necessary to study the fatigue characteristics of rocks under a certain period of action. With an RDL series electronic creep relaxation testing machine, fatigue loading and unloading tests of sandstone at different loading rates were carried out, followed by uniaxial compression on the samples. The study shows that the stress–strain curves of the uniaxial compression specimens have three stages: a compaction pore fracture stage, an elastic deformation stage, and an unstable fracture developing to failure stage. The stress–strain curves of the samples with a certain number of cycles of loading and unloading give the thinning and dense phenomenon, and the axial upper limit strain and axial cumulative residual strain gradually decrease as the loading rate increases. With the increase, the uniaxial compressive strength of the reloaded samples increases gradually, which is higher than the ordinary uniaxial compressive strength. In the process of cyclic loading and unloading, the internal particles of the sample present fracture and reorganization of the fragile structure and, at the same time, compaction stability.