Effect of processing of tail section of tested curve on fracture energy of dam concrete

The design and safety evaluation of dam all require to study the fracture properties of dam con- crete intensively and systematically. The fracture energy G of dam concrete and wet-screened concrete were F investigated in this paper based on our test data of 21 wedge-splitting specimens for 7 groups . Based on the principle of work-of-fracture, the G were calculated by the tested P-CMOD curve. The tested F original curves showed that the measured maximum CMOD of some specimens exceeded capacity of the dis- placement sensor due to employing large size and large size aggregates dam concrete specimens. It led to CMOD value at the tail section curve of some specimens distorted. The tail section of the tested P-CMOD curve need to be fitted, so that the complete P-CMOD curve for calculating fracture energy can be got. Even so, the complete P-CMOD curves of some wedge-splitting specimens can be tested perfectly. The ra- tionality of fitting the tail section of tested P-CMOD curve by power function or exponential function was studied by contrasting between the tested complete P-CMOD curve and the P-CMOD curve whose tail is fit- ted. The following three methods were employed to calculate the fracture energy GF of dam concrete and wet-screened concrete: ①Calculated the GF by the tested P-CMOD curve for each companion specimens, then average the results and got the GF of each specimen group. ② Calculated the GF by the averaged P- CMOD curve of which the tail section was fitted by exponential function. ③ Calculated the GF by the aver- aged P-CMOD curve of which the tail section was fitted by power function. It was found that the GF calculated by the method ② was the nearest to that calculated by the originally tested complete P-CMOD curve. So the GF of dam concrete and wet-screened concrete were identified by the method ②. The size effect of fracture energy of dam concrete and wet-screened concrete, and the relationship of fracture energy between dam concrete and wet-screened concrete were discussed preliminarily.