| Limonite concrete is a special type of concrete that can shield gamma rays,neutrons and other rays.It is widely used in nuclear energy,military,scientific research and many other fields.The risk of explosion,shock,earthquake and other non-design load is increasing in the world today.It is of great significance to carry out the dynamic performance of limonite concrete under impact load.In this paper,the static and dynamic mechanical properties and radiation resistance of limonite concrete are studied experimentally,and the particle flow code（PFC）is used to simulate the dynamic mechanical properties test.The main research contents and conclusions of this paper are as follows:（1）Limonite concrete and ordinary concrete were prepared with the same water-binder ratio.limonite concrete and ordinary concrete were subjected to different age compressive strength tests andγ-ray shielding performance tests.The results show that the compressive strength of limonite concrete at 7d、14d and 28d is greater than that of ordinary concrete,and the strength develops relatively quickly in the early stage of curing.Limonite concrete also has better gamma-ray shielding performance than ordinary concrete.（2）Dynamic compression tests of ordinary concrete and limonite concrete were carried out by using a 100 mm diameter split Hopkinson bar（SHPB）test device.The results show that:the stress-strain curves of limonite concrete and ordinary concrete are very similar,and the peak stress and peak strain gradually increase with the increase of the strain rate,showing an obvious rate dependence.The fitting formula of dynamic magnification factor（DIF）of ordinary concrete and limonite concrete is obtained.It is found that the rate correlation of limonite concrete is stronger than that of ordinary concrete when the strain rate is less than 113.5s-1.When the strain rate is greater than 113.5s-1,the rate correlation of ordinary concrete is stronger.（3）The energy dissipation of ordinary concrete and limonite concrete is analyzed.The results show that the energy absorption capacity of limonite concrete is less than that of ordinary concrete,and the proportion of energy absorbed by concrete in incident energy is certain,which has nothing to do with the air pressure and strain rate.With the increase of strain rate,the failure modes of the two types of concrete develop from breaking into large pieces to breaking into small pieces.Under the same air pressure,because the energy absorption capacity of limonite concrete is less than that of ordinary concrete,the crushing size of limonite concrete is generally larger than that of ordinary concrete.（4）The particle flow code（PFC）was used to emulate the SHPB impact test of limonite concrete.The results indicate that the simulated and experimental stress-strain curves are in good agreement,and the failure process of limonite concrete under different strain rates is reproduced. |
