冲击载荷下张拉预应力红砂岩的动态张拉强度弱化效应  

Dynamic tensile strength weakening effect of pretension stressed red sandstone under impact load

作　　者：伍武星 宫凤强 WU Wu-xing;GONG Feng-qiang(Engineering Research Center of Safety and Protection of Explosion&Impact of Ministry of Education(ERCSPEIME),Southeast University,Nanjing 211189,China;School of Civil Engineering,Southeast University,Nanjing 211189,China;Oulu Mining School,University of Oulu,Oulu 90570,Finland)

机构地区：[1]Engineering Research Center of Safety and Protection of Explosion&Impact of Ministry of Education(ERCSPEIME),Southeast University,Nanjing 211189,China [2]School of Civil Engineering,Southeast University,Nanjing 211189,China [3]Oulu Mining School,University of Oulu,Oulu 90570,Finland

出　　处：《Journal of Central South University》2023年第10期3349-3360,共12页中南大学学报（英文版）

基　　金：Project(42077244)supported by the National Natural Science Foundation of China;Project(202206090157)supported by the China Scholarship Council。

摘　　要：深部围岩的张拉破坏是一种常见的破坏模式,这与深部围岩处于高应力和冲击荷载的组合受力状态密切相关。本研究中,使用分离式霍普金森压杆(SHPB)设备对不同张拉预应力水平下的红砂岩巴西圆盘试样进行不同加载速率下动态张拉试验。基于试验的准静态峰值拉伸应力,确定了试验的张拉预应力水平分别为0,0.48,1.44,2.39,3.45和4.30 MPa,以及400~1200 GPa/s范围内的冲击荷载的加载速率。试验结果表明,动态张拉强度与加载速率呈显著的线性正相关关系,且随着加载速率的增加而逐渐增加,表现出明显的率效应。在相同加载速率下,动态张拉强度随着张拉预应力水平的增加而显著降低,表现出明显的动态张拉强度弱化效应。此外,总结了动态张拉度弱化效应机理,其中张拉预应力水平决定了动态张拉强度弱化水平,而冲击载荷则促进了强度弱化效应的显现。Tension failure of deep surrounding rock is a very common failure mode,which is closely related to the couple of static pre-stress and impact load.Thus,the dynamic tensile strength of pretension stressed Brazilian disc(BD)specimens subjected to the impact load was measured at the couple different pretension levels and loading rates with the modified split Hopkinson pressure bar(SHPB)system.Six groups of Linyi sandstone BD specimen were impacted with the loading rates from 400 to 1200 GPa/s under the pretension of 0,0.48,1.44,2.39,3.45 and 4.30 MPa.The test results reveal the dynamic tensile strength has a very significant linear positive correlation with the loading rate,wherein increases gradually with the loading rate increase,reflecting the obvious rate dependency.The dynamic tensile strength decreased significantly with pretension stress level increase at the same loading rate,showing an obvious dynamic tensile strength weakening effect.Besides,the mechanism of the dynamic tensile strength weakening effect is summarized,wherein the pretension stress level dominates and determines the dynamic tensile strength weakening level,and the impact load induces the appearance of the strength weakening effect.

关 键 词：动态张拉强度 强度弱化效应 BD试样 张拉预应力 冲击载荷 分离式霍普金森压杆(SHPB) 

分 类 号：U44[建筑科学—桥梁与隧道工程]