关键词: 混凝土劈拉试验, 声发射, 损伤演化, ROC曲线, 损伤界点

Abstract: In order to explore the features of concrete dynamic splitting, we carried out splitting test under different strain rates and established the relationship between stress level and AE(acoustic emission) energy number. Then, we put forward the concept of critical damage point and determined the evolution equation of dynamic splitting damage of concrete. On the basis of determining optimal critical point by using medical ROC(receiver-operating characteristic) curve, we gave the stress level of concrete at critical damage point in splitting test. Results showed that 1) under high strain rate, stress lags when emission signal occurs at the first stage of damage; 2) AE phenomena at the second stage were similar to those with low strain rate after stress level exceeded a given value; 3) with the increase of strain rate, the stress level at critical damage point increased, and its range was ; 4) there is a linear relationship between stress level at critical damage point and logarithmic function of strain rate, and the strain rate of concrete at critical damage point in splitting test under stress space was 0.75.

Key words: splitting test, acoustic emission, damage evolution, ROC curve, critical damage point