Study On Mechanical Properties And Damage Characteristics Of Sandstone Under Cyclic Loading

With the continuous deepening of tunnel construction,mine development,water conservancy project,slope support and other fields,sandstone as the most common basic materials in construction.However,sandstones are long-term role in the underground,and the cracks in sandstone have changed,and structural and mechanical properties have changed,so that there are many safety hazards in deep mining,high-speed rail construction,dam use,etc.,studying sandstone cycle,the mechanical properties and damage characteristics of load under load are very important.With the study of sandstone as the research object,the sandstone under different cycle loads in different water content,different stress magnificents,different loading rates,peak strain,axial accumulation residual strain,axial residual strain increment and its corresponding intensity and damage forms are compared,and the link between the combined SEM image is analyzed by the macroscopic breakage characteristics of the rock,discusses the evolution of the rock under cycle load from the microscopic perspective.And the effect of the residual strain of sandstone after the study of the interval during the study of the time interval,and the effect of accumulation residual strain was carried out on the basis of the cyclic load test.The peak strain,elastic modulus,and comparative analysis of sandstone test pieces without cyclic loads being analyzed,and the deterioration of the mechanical properties of sandstone test pieces were analyzed by the anti-continuous circulating load trial.The results show that the rock breaking ring form under cycle load is mainly based on tensile cracking and composite type.Axial accumulated residual strain and peak strain evolved with increased number of cycles,different water rate sandstones,different stress amplitude,different loading rates at different loading rates increase with the increase of cycles,different loading rate axial The residual strain increase decreases as the number of cycles increases.Natural drying,saturated,high temperature drying strength increased by 13.1%,4.1%,8.9%relative to ordinary post-uniaxial compressive strength after cycle.The increase in the increase in cycles with the increase in the increase of the increase in the increase of the increase in the increase of the increase in the increase of the increase in increase,and the strength comparative comparative comparative comparative comparative comparison is also a growth trend.Discussing the evolution law of rock under cycle load from a microscopic perspective,resulting in two phenomena of rock under cyclic load:fragile structural fracture reorganization,compaction and stability.At the discontinuous cycle,the time interval has an accelerated residual strain,the longer the time interval,the faster the accumulation speed of the residual strain,the flexible modulus of the elastic modulus after the time interval is large,and the interval increases.The ability of the sandstone resistance to the circulating load deterioration,the pressure strength of the rock is reduced,and the brittleness is enhanced,so that the overall mechanical properties of the rock have deteriorated,affecting the overall stability of the rock structure.Figure[44];Table[10];Reference[88]...