Study On Meso - Numerical Simulation Of Double - K Fracture Parameters Of Concrete

From the microscopic perspective, the concrete can be seen as a complex three-phase non-homogeneous material from the joint surface aggregate, mortar, between the front thereof. Since the concrete composition of different materials with different physical characteristics, which determines the mechanical properties of concrete complex, together with the surrounding environment, and other external loads applied to the case that the failure mechanism of concrete become more complex, its study of fracture mechanism It adds great difficulty. Taking into account the concrete itself has a number of advantages in its use, its structural safety, skills and the value of economic rationality can not be ignored social significance, and is widely used in civil engineering. This requires researchers fracture mechanism of concrete in-depth study, so that it can be used for the national economy. In recent years, the microstructure of concrete fracture mechanics-based recognition and gradually mature. This paper focuses on concrete double-K fracture parameters were the following studies:(1) This selection of concrete meso random aggregate model, the structure and properties of concrete were calculated. Meso-level departure from habit, concrete is regarded as a three-phase composite material for the two-dimensional random polygon aggregate model, further studies of its crack propagation. Using MATLAB the original oval base polygon aggregate generator reprogramming random polygonal aggregate generation program, the optimization of polygonal aggregate generating method to improve the accuracy of the calculation;(2) By analyzing the advantages and disadvantages of different fracture models, including virtual fracture model, fault model (CBM), two parameter fracture theory (TPFM), equivalent fracture model (ECM) and size effect model (SEM) and so on, this article selected double K model parameters were calculated and analyzed fracture toughness of concrete;(3) the use of small size of the model of soil use of existing test model to simulate the size, the use of double-K fracture model calculation double K parameters, test results within an allowable range;(4) the use of large size models, with different slot height ratio, using the finite element software ABAQUS damage fracture models for concrete and structural finite element analysis and calculation, using two K model calculation of double-K fracture parameters, that is, from fracture toughness parameters and fracture toughness parameters, analyze the different seams higher than aggregate different content, different shapes of concrete aggregate failure modes;(5) by corresponding calculation results, the curves obtained from the impact of concrete cracking and fracture toughness factor stable fracture toughness, provide a strong basis for the study of concrete macro-cracks.