Hu Anlong, Xue Guobin, Shang Zhipeng, Cao Zhe, Wang Xiaoping, Fu Yintao, Huang Xiaoqing
Economic and Technological Research Institute of State Grid Gansu Electric Power Company, Lanzhou, 730050, Gansu, China.
Key Laboratory of Geological Hazards On Three Reservoir Area, Ministry of Education, China Three Gorges University, Yichang, 443002, Hubei, China.
Sci Rep. 2023 Oct 25;13(1):18280. doi: 10.1038/s41598-023-45576-4.
In China's cold region water conservancy and hydropower projects, the contact interface between the dam and the reservoir bank rock is prone to cracking under external loading and freeze-thaw action, which may lead to dam-bank failure and damage and cause engineering disasters. The NMR (Nuclear Magnetic Resonance) tests and uniaxial compression tests of concrete, sandstone, and sandstone-concrete composite after different numbers of freeze-thaw cycles were carried out to analyze the pore structure development and uniaxial compression mechanical properties of the three types of specimens under different numbers of freeze-thaw cycles. The results show that freeze-thaw cycling promotes the development of pores in sandstone and concrete, and sandstone is more sensitive to low-temperature freeze-thaw than concrete. The UCS (uniaxial compressive strength) of the sandstone-concrete binary changed in a V-shaped with the increase of the dip angle of the cemented interface, and the angle had no obvious effect on the microscopic pores. The freeze-thaw effect on the deterioration of the microscopic pore structure and mechanical properties of the sandstone-concrete binary has a similar effect pattern, in which the deterioration rate of porosity and compressive strength is faster in the early freeze-thaw period, slower in the middle period, and increases in the later period compared with the middle period, but the increase is smaller than that in the early period of freeze-thaw. In addition, the relationship between the porosity and UCS of the sandstone-concrete binary under the freeze-thaw cycle environment is a quadratic parabola.
在中国寒冷地区水利水电工程中，大坝与库岸岩体的接触界面在外部荷载和冻融作用下容易产生裂缝，可能导致坝岸失稳破坏，引发工程灾害。通过对混凝土、砂岩以及砂岩 - 混凝土复合体在不同冻融循环次数后的核磁共振（NMR）试验和单轴压缩试验，分析了三种类型试件在不同冻融循环次数下的孔隙结构发展及单轴压缩力学性能。结果表明，冻融循环促使砂岩和混凝土内部孔隙发展，且砂岩对低温冻融比混凝土更敏感。砂岩 - 混凝土二元体的单轴抗压强度（UCS）随胶结面倾角增大呈V形变化，该倾角对微观孔隙无明显影响。冻融作用对砂岩 - 混凝土二元体微观孔隙结构劣化及力学性能的影响规律相似，其中孔隙率和抗压强度的劣化速率在冻融前期较快，中期较慢，后期相较于中期有所增加，但增幅小于冻融前期。此外，冻融循环环境下砂岩 - 混凝土二元体的孔隙率与单轴抗压强度之间的关系为二次抛物线关系。
