对酸热处理后的黄砂岩试样进行了物性测试、单轴压缩试验、SEM扫描和工业CT测试,探讨了酸热作用对黄砂岩物理力学性质的影响,揭示了酸热作用后黄砂岩试样的微观损伤机制,结果表明:受酸热共同作用后黄砂岩试样质量和纵波波速均随温度升高而不断降低,而孔隙率则随温度升高而增大;与仅受高温作用的黄砂岩相比,遭受酸热共同作用的黄砂岩峰值强度、弹性模量、峰值应变均会进一步劣化;酸热作用下黄砂岩的微观损伤表现为试样中裂纹以及孔隙的扩展;高温热应力会在岩样内部和表面产生热致裂纹,从而削弱矿物颗粒间的粘结性,增大试样孔隙率和延性,降低试样的纵波波速和强度;当加热温度超过石英矿物相变温度时,石英矿物相变会加快热致裂纹的萌生和扩展,导致黄砂岩不可逆热损伤的加速发展;酸性溶液的侵蚀会在岩样中产生酸致裂纹,同时造成热致裂纹的二次扩展,从而加剧了黄砂岩力学性能的劣化。
The physical property test, uniaxial compression test, SEM scanning and industrial CT test were carried out on the yellow sandstone samples after acid and heat treatment. The effect of acid-heat action on the physical and mechanical properties of yellow sandstone was discussed, and the microscopic damage mechanism of yellow sandstone samples was revealed after acid-heat action. The test results show that: Both the mass and p-wave velocity of yellow sandstone samples decreased with the increase in temperature, while the porosity increased with the increase in temperature. Compared with yellow sandstones subjected only to high temperature, the peak strength, elastic modulus and peak strain of yellow sandstones subjected to the combined action of acid and heat will be further deteriorated. The microscopic damage of yellow sandstone under the action of acid-heat is characterized by cracks and pore expansion in samples. Thermal stress induced by high temperature will produce thermal cracks inside and on the surface of the rock sample, which weakens the cohesiveness between mineral particles and increases the porosity and ductility of the sample and reduces the P-wave velocity and strength of the sample. When the heating temperature exceeds the quartz mineral phase transition temperature, the phase transition of quartz minerals will accelerate the initiation and propagation of thermal cracks, and further the development of irreversible thermal damage of yellow sandstone. The erosion of the acid solution will produce acid-induced cracks in rock samples, and at the same time cause the secondary propagation of heat-induced cracks, which intensifies the deterioration of the mechanical properties of yellow sandstone.
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