Methods For Confirming Parameters Of Dynamic Damage Constitutive Model For RCC Under High Strain Rates

Roller compacted concrete is a harsh lean cement concrete. Its characteristics are small volume, high strength, good anti-seepage performance and construction, and widely used in hydraulic dam. Due to the unique composition and diversion of RCC, and using of the RCC construction technology, its deformation and strength characteristics all have some difference with normal concrete. Especially in the extreme loads of instantaneous load, the mechanical response is hard to predict, dynamic mechanics property is complex, so it needs further study. Based on the fully research SHPB(Split Hopkinson Pressure Bar) to be improved after the experiment principle, and the improved SHPB test technology was used to study the dynamic strength of roller compacted concrete under high strain rate and strain rate sensitivity of the size effect. Then comparing the mechanical properties of normal concrete under different loading rate, finally combining SHPB experimental technology, theoretical analysis and numerical simulation technology, comparing with the laboratory test, it put forward the method to determine the parameter of the dynamic damage constitutive model for RCC.In this paper, the basic research achievements are the following four aspects:1?For the problem that SHPB experimental technique with the large size exists radial and axial inertial effect, stress wave dispersion and Bob stress at the time of data processing when the determination of the dynamic mechanical properties2?Using the loading way of half sinusoidal stress wave with wavelength proportional to the length of concrete specimen. Perform SHPB experiment for the specimen with different dimensions under high strain rate to research the dynamic strength and the size effect of the strain rate sensitivity of RCC.3?Compare the strength and damage characteristics of RCC and normal concrete under different loading rate and failure characteristics, and study the dynamic mechanical properties and damage mechanism, mechanical model, the characteristic parameters of RCC and normal concrete under impact load. It provides the test basis for the study of failure mechanism of roller compacted concrete constitutive model and the dam with high strain rate.4?Combining with SHPB test results, test data of theoretical analysis and numerical simulation technology, The experimental device of SHPB is built, which is three-dimensional finite element model. On the simulated analysis of the experiment, by comparing with the laboratory test, it verifies the validity of the numerical model, and research different strength grade material constitutive model parameters of roller compacted concrete, so that put forward the dynamic damage constitutive model of material parameters, in order to make up for the inadequacy of indoor test.