Study On Induced Joints And Fracture Property Of Layer Surface In RCC With Test And Numerical Modeling

In recent years, the construction technique using RCC (Roller Compacted Concrete) in dam engineering, which combines the advantages of concrete dam and embankment dam, has exhibit obvious superiority. So that it is widely used in hydraulic engineering. However, many problems lying in the design and construction of RCC arch dams and gravity dams are to be lucubrated. At present, many difficulties still exists in the research on the equivalent strength model of induced joints for RCC arch dam. Moreover, the fracture stable analysis on the dam layer becomes more and more significant due to the durative increasing of the height and layers of RCC gravity dams. Considering these problems, research works are done in this dissertation with test and numerical simulation methods, funded by the National Natural Science Foundation of China— Study on equivalent strength of induced joint in RCC arch dam (50179002):1. Study on the equivalent strength of non-penetrated induced jointsThe unaxial tensile tests of RCC specimens preplacing two kinds of non-penetrated rectangular induced joints are performed. According to the test data, the approximate analytical formulas of stress intensity factor for RCC specimens with two directional adjacent non-penetrated rectangular induced joints are established. Then, the correction coefficients of fracture parameters are deduced. Finally, using the elliptic crack model for infinite embedded body and the double parameter fracture criterion, the double parameter equivalent strength applicable to fracture analysis of the RCC arch dams are deduced.2. Numerical simulation of the setting of induced jointsUsing the software MFPA^2D , which can realize the full process analysis of material fracture, the variation of stress field as well as the initiation and propagation direction of the induced joints under tension and shearing are simulated. During the simulation, the variety of the length and spacing of the preformed joints as well as the inter-coupling of adjacent cracks are all considered. Then, consulting the results of simulation, the more reasonable setting of induced joints is determined.3. Test and simulation of the mode I interlaminar fracture properties of RCCCorresponding fracture parameters are gained by performing mode I interlaminar fracture tests of RCC of seven operating modes. From the point of microcosmic, numerical simulation of the mode I interlaminar fracture process of the layer surface joints 2 and 3 of RCC is also performed using MFPA2D software. Referring to experimental data and numerical simulation results, the differences of mode I fracture parameters and failure forms of layer surface of various operating modes was investigated. And the simulation results fit the test data well. It can be draw from the comparing of the simulation results and the test data that the initial fracture loads determined by electric determination is of great reference to the confirming of initial fracture toughness.4. Test and simulation of the mode II interlaminar fracture properties of RCCCorresponding fracture parameters are gained by performing mode II interlaminar fracture tests of RCC of seven operating modes. From the point of microcosmic, numerical simulation of the mode II interlaminar fracture process of the layer surface joints 2 and 3 of RCC is also performed using MFPA2D software. Referring to experimental data and numerical simulation results, the differences of mode II fracture parameters and failure forms of layer surface of various operating modes was investigated. And the simulation results fit the test data well.5. Test and simulation of the multiplex mode I-II interlaminar fracture properties of RCCCorresponding critical multiplex stress intensity factors together with formulas of multiplex mode I-II fracture curves to characterize the relationship between and are calculated by performing multiplex mode I-II interlaminar fracture tests of RCC of seven operating modes. From the point of microcosmic, numerical simulation of the multiplex mode I-II interlaminar fracture process of the layer surface joints 2 and 3 of RCC is also performed using MFPA2D software. Referring to experimental data and numerical simulation results, the differences of mode II fracture parameters and failure forms of layer surface of various operating modes was investigated. The criterion of multiplex mode I-II interlaminar fracture of the layer surface joints 2 and 3 of RCC is found. And the simulation results fit the test data well.