基于SHPB实验的岩石峰后动态行为研究.pdfVIP

Trans. Nonferrous Met. Soc. China 27(2017) 184−196 Dynamic behavior of rock during its post failure stage in SHPB tests Zi-long ZHOU1 1 2 3 1 1 , Yuan ZHAO , Yi-hui JIANG , Yang ZOU , Xin CAI , Di-yuan LI 1. School of Resources and Safety Engineering, Central South University, Changsha 410083, China; 2. China Railway Engineering Consulting Group Co., Ltd., Beijing 100000, China; 3. École Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering, Lausanne CH-1015, Switzerland Received 20 November 20 15; accepted 9 October 2016 Abstract: In order to investigate the micro-process and inner mechanism of rock failure under impact loading, the laboratory tests were carried out on an improved split Hopkinson pressure bar (SHPB) system with synchronized measurement devices including a high-speed camera and a dynamic strain meter. The experimental results show that the specimens were in the state of good stress equilibrium during the post failure stage even when visible cracks were forming in the specimens. Rock specimens broke into strips but still could bear the external stress and keep force balance. Meanwhile, numerical tests with particle flow code (PFC) revealed that the failure process of rocks can be described by the evolution of micro-fractures. Shear cracks emerged firstly and stopped developing when the external stress was not high enough. Tensile cracks, however, emerged when the rock specimen reached its peak strength and played an important role in controlling the ultimate failure during the post failure stage. Key words