基于数值模拟研究岩石材料冲击载荷下的动态抗压强度增强

Investigation on Dynamic Compressive Strength Enhancement of Rock Materials Under Impact Loading Based on Numerical Simulations

为了确定岩石材料在SHPB实验中的真实应变率效应,需要去除实验中的横向惯性效应和端面摩擦效应作用引起的动态抗压强度增量。本文假定材料的真实应变率效应、横向惯性效应和端面摩擦效应三者不相关,基于数值模拟的方法确定岩石材料的横向惯性效应和端面摩擦效应。将从SHPB实验中得到的动态抗压强度数据减去分别由横向惯性效应和端面摩擦效应引起的动态压缩强度增强量,即可获得岩石类材料在SHPB实验中的真实应变率效应。

Rock materials will unavoidably subjected to blast and impact loadings during the mining activities, and thus damage will be induced. Split Hopkinson pressure bar （SHPB） technique is often used to characterize the dynamic compressive strength of rock materials under impact loading. Many experimental results showed that, the dynamic compressive strength of rock materials increase with the increase of testing strain-rate. Besides, it has been found recently that the dynamic compressive strength enhancement of rock materials under impact loading is due to the combined effects of material strain-rate, lateral inertial and end friction, and in SHPB tests they are coupled together and could not be separated from each other. To determine the material strain-rate effect of the rock materials themselves in SHPB tests, the dynamic compressive strength enhancement caused by lateral inertial effect and end friction effect needs to be removed. Assuming that the effect of material strain-rate, lateral inertia and end friction is uncoupled, the numerical simulation method is employed to simulate the SHPB tests on rock materials. Thus, the lateral inertial effect and end friction effect can be separately determined with the method of numerical simulations. Then removing the dynamic compressive strength enhancement caused respectively by the lateral inertial effect and end friction effect from the dynamic compressive strength data obtained from actual SHPB tests, the material strain-rate effect of the rock materials in SHPB tests is determined.