To improve the long-term performance of concrete engineering in high-altitude areas, waste tire rubber was added to a concrete mix, and freeze–thaw and impact tests were conducted. The effects of waste tire rubber with different particle sizes (10, 20, 30 mesh) and freeze–thaw cycles (0, 25, 50, 75, 100, 125) on the dynamic mechanical properties of concrete materials were studied. The stress–strain curves, peak stress, and fracture morphology of the specimens were analyzed. The microstructure changes of the specimens were also analyzed using scanning electron microscopy (SEM). The results showed the following: (1) Both macroscopic and microscopic analysis results showed that the internal damage of rubber concrete specimens was smaller after freeze–thawing, and the integrity was better after impact, maintaining a loose but not scattered state. The addition of waste tire rubber significantly improved the material’s impact resistance to a certain extent. (2) As the impact pressure increased, the strain rate of the specimens increased linearly, and the dynamic peak stress was linearly positively correlated with the strain rate. (3) After 125 freeze–thaw cycles, the peak stress of the specimens with 30-mesh added rubber decreased significantly less than that of ordinary concrete under 0.3, 0.45, and 0.6 MPa impact pressure. The dynamic peak stress was higher than that of specimens with 10-mesh and 20-mesh added rubber, and the addition of 30-mesh rubber significantly improved the frost resistance and impact resistance of concrete materials. This study can provide new ideas for the engineering application of rubber concrete.

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.

At present, many studies have been carried out on the fatigue mechanical properties of conventional rocks, but there are few studies on the mechanical properties of rocks after water rock interaction. The aim is to better study the fatigue mechanical characteristics of sandstone after dry wet cycle and the research object we take was sandstone samples after a certain number of drying and wetting cycles. The WAW-2000 electro-hydraulic servo pressure system was used to carry out uniaxial fatigue cyclic loading and unloading tests with different amplitudes and different upper limit stresses. The test found that: when the sample is damaged under fatigue load, the stress-strain curve shows a sharp downward trend and a sudden instability failure occurred in the sample.With the increase of the upper limit stress and amplitude, the life of the sample decreases gradually which also conforms to the change of power function. Then the relationship between fatigue life and stress is obtained. The fatigue stress-strain curve is characterized by sparse-dense-sparse. With the increase of cycle time, the axial strain of the sample shows an inverted “S” shape. The strain change can be divided into three stages: initial stage, constant velocity stage and acceleration stage.

The physical properties of solidified mud will deteriorate under the combined action of freezing-thawing cycle and chlorine salt, which will affect the safety and stability of solidified mud engineering. In order to study the damage characteristics of solidified mud under the action of freeze-thaw cycle and chloride salt, the solidified mud samples were soaked in different concentrations of sodium chloride solution and treated with freeze-thaw cycle. Besides, the unconfined compressive strength test was carried out to study the damage characteristics of the samples caused by different concentrations of sodium chloride solution and freeze-thaw cycles. The test results show the following. (1) Under the action of freeze-thaw cycle and sodium chloride solution, the surface of the sample deteriorated in varying degrees. With the increase in freeze-thaw cycle times and sodium chloride solution concentration, the mass loss of the sample was greater. (2) Under the action of chlorine salt and freeze-thaw cycle, the strength of the sample decreases with the increase in freeze-thaw cycle times. With the increase in the concentration of sodium chloride solution, the strength of the sample decreases and the damage degree increases gradually. (3) Under the action of freeze-thaw cycle, the internal pores of the samples gradually expand and more honeycomb holes appear, and the content of hydration products is higher. As the concentration of sodium chloride solution increases, the particle connection inside the sample gradually weakens, and the sample is more likely to be damaged.

In order to study the law of influence of rubber particle size on concrete frost resistance characteristics, this paper systematically evaluates the freeze–thaw characteristics of rubber concrete containing different particle sizes. Rubber concrete containing different particle sizes is subjected to 25, 50, 75, 100, and 125 freeze–thaw cycles. After the freeze–thaw cycles, the specimens are observed or measured for appearance, mass change rate, relative dynamic elastic modulus, internal damage degree, compressive strength, and tensile strength. The results show that the frost resistance of concrete mixed with rubber of different particle sizes is more excellent, and the surface of concrete specimens after different numbers of freezing and thawing cycles shows different degrees of spalling. Meanwhile, due to the presence of rubber, the compressive and tensile strengths of rubberized concrete are significantly inferior. Finally, the microscopic scanning results reveal the mechanism of rubber’s incorporation into concrete. The incorporation of rubber effectively reduces its internal pore development. To summarize, it can be seen that rubber incorporated into concrete is a worthwhile method to consider for frost resistance of engineering materials.