Estimation of real fracture parameters of a dam concrete with large size aggregates through wedge splitting tests of drilled cylindrical specimens

摘要

For dam concrete with large size aggregates, large specimen tests are required to obtain size-independent fracture parameters, which are difficult to conduct and such large specimens by no means can be drilled from the dam. The current work attempts to use the results of wedge-splitting tests on 300 mm-diameter cylindrical compact tension specimens drilled from Danjiangkou Dam to extrapolate the real fracture parameters that are required to assess the safety of the dam. Load-CMOD curves were obtained from the tests and the experimental double-K fracture parameters were evaluated. For this dam concrete whose maximum aggregate size is 150 mm, the experimental double-Ks from these relatively small compact specimens would be underestimated. To overcome this problem, a numerical analysis was performed using a cohesive model. The experimental load-CMOD curves were deeply analyzed to obtain the required softening parameters in the cohesive model, in particular the extension of the tail to calculate the non-measured portion of the fracture energy. With the cohesive model generating the load-CMOD curves for different specimen sizes, the double-K parameters for large sizes were computed, which are applicable for safety assessment of practical structures. (C) 2016 Elsevier Ltd. All rights reserved.