In order to study on the problems of cracking similarity conditions and test simulating method of induced joint in structural model test, fracture property tests of material and mechanics theory deducing are presented in this paper. According to the similarity criterion of structural model test, prototype material and model material need to conform to the similarity conditions of fracture property and shear friction strength. The fracture toughness of RCC, considering the size effect, and the curve of water-gypsum ratio vs. fracture toughness of gypsum are obtained by material fracture tests. Furthermore, theory of fracture mechanics is used to analyze the relation between fracture toughness and stress intensity factor, the similarity conditions of cracking property is deduced, and the model sizes of induced joint, conformed to the cracking conditions, is calculated. In the test, a copper sheet cover with mylar is used as the joint material and the shear-friction strength similarity condition is satisfied by considering the comprehensive effects of f and c. Consequently, cracking similarity simulation of induced joint is realized in structural model test. The results provide the basis for researching cracking and failure mechanism of RCC arch dam with induced joints.
