Experimental and numerical investigation on the dynamic shear failure mechanism of sandstone using short beam compression specimen  

作　　者：Zelin Yan Feng Dai Yi Liu 

机构地区：[1]State Key Laboratory of Hydraulics and Mountain River Engineering,College of Water Resource and Hydropower,Sichuan University,Chengdu,610065,China

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2023年第8期1911-1923,共13页岩石力学与岩土工程学报（英文版）

基　　金：The authors thank the financial support from the National Natural Science Foundation of China(Grant.Nos.52039007 and 52225904);the Youth Science and Technology Innovation Research Team Fund of Sichuan Province(Grant.No.2020JDTD0001).

摘　　要：In this study,a novel testing method is proposed to characterize the dynamic shear property and failure mechanism of rocks by introducing the short beam compression(SBC)specimen into the split Hopkinson pressure bar(SHPB)system.Firstly,the stress distribution of SBC specimen is comprehensively analyzed by finite element method(FEM),and the results show that the optimal notch separation ratio of SBC specimen is C/H?0.2 to achieve successful dynamic simple-shear tests.Then,dynamic shear tests are conducted on sandstone using the SBC-SHPB method.Via careful pulse shaping technique,the dynamic force balance is guaranteed for SBC specimens,and the testing results show that the dynamic shear strength of sandstone is significantly rate-dependent.Combining the results of dynamic compression and tension tests,the failure envelopes of sandstone under different loading rates are obtained in the principle stress plane.It is found that the failure envelope of sandstone constantly expands outwards with increasing loading rate.Moreover,the energy partition of SBC specimen is quantified by virtue of high-speed digital image correlation(DIC)technique.The results show that the kinetic energy portion is non-negligible,and the shear fracture energy increases with increasing loading rate.In addition,the microscopic shear cracking mechanism of SBC specimen is analyzed by the thin section observation:the intra-granular(TG)fracture of minerals dominates the dynamic shear failure of sandstone,and the portion of TG fracture increases with increasing loading rate.This study provides a convenient and reliable method to investigate the dynamic shear property and failure mechanism of rocks.

关 键 词：Dynamic shear property Short beam compression(SBC) Dynamic fracture energy Micro-cracking mechanism 

分 类 号：TU45[建筑科学—岩土工程]