一维应力预加载下红砂岩冲击力学特性试验研究

Experimental Investigation on Impact Dynamics Properties of Red Sandstone Subjected to One-Dimensional Stress Preloading

为研究高地应力下再受动力扰动的岩石力学特性,利用改进的岩石动静组合加载SHPB试验装置,对红砂岩进行一维预应力状态下岩石的冲击力学特性试验。选取4个轴压水平,进行不同应变率下的动加载试验。研究结果表明:不同应变率下,岩样在破坏阶段出现"峰后塑性"、"应力跌落"、"应变回弹"三种类型,岩样的割线模量随轴压的增大先增大后减小;相同轴压下,岩样的动态抗压强度和单位体积吸收能随着应变率的增大而增大,分别呈现出指数函数关系和线性关系;相同应变率下,岩样的动态抗压强度和单位体积吸收能随着轴压的增大呈先增大后减小的趋势;无轴压条件下,岩样为拉伸破坏模式,有轴压条件下,岩样为剪切破坏模式。

In order to study the mechanical properties of rock subjected to high in-situ stress and dynamic disturbance,impact dynamics property experiment of red sandstone subjected to onedimensional stress preloading was carried out by using a improved split Hopkinson pressure bar（SHPB）,which can realize static and dynamic combined loading for rock samples.Four axial compression levels were selected,and dynamic loading experiment was carried out at different strain rates.Results show that at different strain rates,at the failure stage,rock samples present three failure modes,i.e.＂post-peak plasticity＂,＂stress drop＂and＂strain rebound＂mode respectively;the secant modulus increases first and then decreases along with the increase of axial compression;under the same axial compression,the rock dynamic compression strength and unit volume absorption energy increase with the increase of strain rate,and present exponential function relation and linear relation,respectively;at the same strain rate,the rock dynamic compression strength and unit volume absorption energy increase first and then decrease with the increase of axial compression;without axial compression,rock samples present tension failure mode;under axial compression,rock samples present shear failure mode.