高温-水冷却循环作用下砂岩物理力学性能和损伤特征研究OA北大核心CSTPCD

Objectives To study the physical and mechanical characteristics of sandstone under multiple high temperature-water cooling cycles,Methods the sandstone was subjected to high temperature-water cooling cycle tests at 200～600℃.The influence of these cycles on the physical and mechanical properties of sand-stone samples was analyzed using ultrasonic longitudinal wave velocity test,physical parameter measure-ments,and uniaxial compression tests.Results The results showed that the mass loss of sandstone samples was lower at temperatures below 400℃,but became more significant at temperatures above 400℃.As both the temperature and the number of high temperature-water cooling cycles increased,the mass loss rate of the sandstone samples increased,and the longitudinal wave velocity decreased.The elastic modulus and compressive strength of the samples decreased rapidly at 600℃,with a temperature threshold affecting these properties between 500～600℃.At 200℃,the strength of the sandstone samples increased with the number of cycles,but when the temperature exceeded 200℃,the damage increased with the number of cycles.The uniaxial failure mode of the sandstone samples was primarily shear-tension composite failure.With more cycles,the failure mode transferred to conical shear failure,and higher temperatures resulted in larger conical failure blocks.Conclusions The study indicated that the physical and mechanical properties of sandstone samples deteriorated significantly after high temperature-water cooling cycles.