基于SHPB的复合岩样动态力学特性数值模拟

复合岩层的动态破坏问题在工程中越来越多,因此研究其动态破坏机理很有必要。采用PFC^2D软件建立分离式霍普金森压杆(SHPB)数值模型,模拟了复合岩层试样在不同倾角及不同应变率下的动态破坏过程。研究表明:随岩层倾角的增大,复合岩层试样动态抗压强度、动态弹性模量曲线整体呈先减小后增大的近“V”字型变化;动态抗压强度随着应变率的增加而增大,而动态弹性模量受应变率的影响较小;复合岩样裂纹以拉伸为主,随着应变率的增大,试样的动态破坏破碎程度越来越严重;试样的宏观破坏模式受细观裂纹的数量及贯通情况综合影响。研究结果有助于理解复合岩层动态破坏规律。

Numerical Simulation on Dynamic Mechanical Properties of Mixed Rock Strata Based on Split Hopkinson Pressure Bar Test

As the dynamic destruction of mixed rock strata are increasingly observed in engineering, it is indispensible to study the mechanism of dynamic destruction. A numerical model of split Hopkinson pressure bar (SHPB) was established by PFC^2D to simulate the dynamic failure process of mixed rock strata specimens with different dip angles of rock strata at varied strain rates. The conclusions are drawn from numerical simulation as follows: 1) as the dip angle of mixed rock strata increased, the dynamic compressive strength and dynamic elastic modulus reduced at first and then surged, displaying a “V”-shaped curve; 2) dynamic compressive strength increased correspondingly with the climbing of strain rate, while dynamic elastic modulus is less affected by strain rate; 3) the cracks of mixed rock strata were dominantly tensile cracks, and dynamic fragmentation exacerbated with the increasing of strain rate; 4) the macroscopic failure mode of specimen was affected by the number and coalescence of cracks. The research findings are conducive to understanding the dynamic failure mechanism in mixed rock strata.