科研之友
微信
新浪微博
Facebook
分享链接
摘要
In the cold regions of western China, initial damages, such as fissures, are ubiquitous in the rock mass, while the combined effects of load and freeze-thaw will greatly weaken the strength of rock mass and cause engineering disasters. To quantify and evaluate the influences of cyclic load and freeze-thaw cycles on the pore parameters and mechanical properties of different damaged rock masses in cold regions, nuclear magnetic resonance technology was used to test the microscopic pore parameters (such as the porosity and T2 spectrum distribution) of red sandstone at the initial damage stage, cyclic load stage and freeze-thaw cycle stage. Subsequently, the damaged samples were subjected to uniaxial loading with acoustic emission monitoring. The test results show that the pore structure and mechanical properties of red sandstones with different initial damage demonstrate consistent behaviors under the sequential action of cyclic load and freeze-thaw cycles. The porosity increases for the samples subjected to cyclic mechanical loading, due to the expansion of original pores. The porosity continues to increase for red sandstone subjected to freeze-thaw cycles, resulting from the newly generated small pores and expansion of original pores. In general, both cyclic load and freeze-thaw cycles can deteriorate the strength and elastic modulus of the samples. The strength reduction of the red sandstone was 5%～10% when subjected to freeze-thaw cycles, and was 20%～30%, under the combined load and freeze-thaw cycles. The lower the initial strength of red sandstone with different fracture damage, the greater the damage of the sample relative to the initial strength after being subjected to load and freeze-thaw. The sandstone samples were found to experience greater damage with the lower initial strength when subjected to load and freeze-thaw. In addition, the porosity increment of the samples subjected to the combined load and freeze-thaw cycles is found positively correlated with the decrease in the sample strength. The above research results can provide an important basis to achieve stable design and safe construction of engineering in cold regions of China. ? 2022 Editorial Department of Journal of Sichuan University.
- 单位
