Experimental Study On Compression Drop Of Barite Concrete And Numerical Simulation

As a new type of special material with shielding radiation material,barite is widely used in the construction of national defense safety engineering,such as nuclear power station.Therefore,it is important to study the dynamic compressive mechanical properties of Barite Concrete under impact loading.In this paper,a series of studies have been carried out by the method of drop hammer impact test and discrete element numerical simulation.The main contents are as follows:(1)The loading test of Barite Concrete and ordinary concrete under static load,and the related material test of barite are completed.The test results show that barite material meets the requirements of relevant codes,and the compressive strength and axial compressive strength of barite concrete are similar to those of ordinary concrete on the premise of the same water cement ratio.(2)The application of drop hammer loading test machine,the dynamic compression impact test of barite concrete and common concrete prismatic specimens with the strain rate range of 1.02S-1 ~ 3.02S-1 and 1.4S-1 ~ 3.8S-1 are completed respectively.The test results show that the peak load,the loading rate and the longitudinal strain peak value of the specimen increase with the increase of the impact height of the drop hammer.(3)Through the analysis of high-speed photography and static failure images,it is found that when the impact height is relatively low,the longitudinal fracture failure is the main reason for the specimen,and the splitting crack continues to extend with the increase of the impact height.With the increase of impact height,the number of longitudinal cracks increases significantly,the bearing capacity of concrete drops sharply,the cracks in the concrete expand continuously,and the macro slanted cracks are formed along the weak surface,and the width of the cracks is increasing,which becomes a damaged zone and the width of cracks increases.The specimens are then broken into multiple fragments,which completely lose their bearing capacity.(4)Through the analysis of the impact test results of plate specimens,it is concluded that the specimens of plate and prism have similar failure laws.High speed video recording results show that the development of cracks is different from ordinary concrete due to their physical properties of brittle aggregates.Besides the development along the interface,the barren concrete is also run through aggregates.(5)Comparative analysis of the compressive impact data of Barite Concrete and ordinary concrete specimens in the same condition.The results show that the Barite Concrete and ordinary concrete has a good correlation between the rate,DIF value increased with the strain rate of growth and growth.(6)The test results show that the surface damage crack of barite concrete specimen and common concrete specimen under different impact conditions has fractal characteristic.With the increase of the strain rate and the impact load,the fractal dimension of the crack increases.(7)The PFC2 D discrete element software is used to simulate the impact test of the barite concrete under different impact conditions,and the results are compared with the test results.The feasibility of the PFC discrete element software in the analysis of dynamic compression test is verified.