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利用多功能三轴仪进行了不同应变速率下的混凝土循环加卸载试验,对声发射信号与应力水平的关系进行了分析,并从声发射撞击数的角度对混凝土损伤演化规律特性进行研究,进一步构建了只含循环次数的单参数损伤值估计模型。研究结果表明:在不同的应变速率下,混凝土损伤演化的路径各不相同,当应变较小时,混凝土前期损伤累积程度较大,后期平缓,出现水平段;随着应变速率的提高,混凝土损伤演化路径前移,后一种应变速率相对于前一应变速率所对应的损伤推移值随着累计残余应变的增大呈现出先增大后减小的规律,当累计残余应变一定的情况下,随着应变速率的提高,相邻2种应变速率对应的损伤推移程度在不断减弱;混凝土循环加卸载损伤演化规律具有三阶段损伤模式,统计密度函数能较好地反映循环加卸载损伤演化规律。
The cyclic loading and unloading tests of concrete under different strain rates were carried out with the multifunctional triaxial apparatus. The relationship between the acoustic emission signal and the stress level was analyzed, and the law of damage and evolution of concrete was studied from the point of acoustic emission impact number. A one-parameter damage damage estimation model with only number of cycles is constructed. The results show that under different strain rates, the path of damage evolution of concrete varies. When the strain is small, the damage accumulates in the early stage of concrete and the horizontal section appears later. With the increase of strain rate, the damage evolution of concrete The path of advance of the latter strain rate corresponding to the previous strain rate shows a law of first increasing and then decreasing with the increase of the accumulated residual strain. When the cumulative residual strain is constant, The strain rate corresponding to two adjacent strain rates is continuously decreasing. The evolution of cyclic loading and unloading damage has a three-stage damage model. The statistical density function can better reflect the evolution of cyclic loading and unloading damage.