摘要
采用波长与岩石试件长度成比例的半正弦应力波加载方式,对长径比为0.5、直径分别为22,36,75 mm的花岗岩、砂岩和石灰岩试件进行不同应变率条件下的SHPB试验。试验结果表明:岩石动态强度随着应变率的增高近似以乘幂关系增大,呈现较强的率依赖性;试件尺寸越大,岩石动态强度对应变率依赖的灵敏性越显著,所测得的岩石动态强度离散性越小;在相同的应变率加载条件下,岩石动态强度随试件尺寸的增大而增加,与静载条件下岩石强度的尺寸效应相反;岩石动态强度的尺寸效应随着应变率的降低而减弱,并由此推断存在一个临界应变率对应着岩石尺寸效应的消失。低于临界应变率时,静载的尺寸效应占主导地位;高于临界应变率时,动态的尺寸效应占主导地位。
Size effect of rock static strength is validated by carrying out the conventional static loading tests on granite, sandstone and limestone specimens with diameters of 22, 36 and 75 mm respectively and a constant length-diameter ratio of 0.5. In order to investigate the rock dynamic strength size effect and the strain-rate sensitivity subjected to axial impact, half-sine stress waveform with wave length proportioned to the specimens＇ length is chose as the loading method to carry out a series of split hopkinson pressure bars（SHPB） tests under different strain rates on granite, sandstone and limestone specimens with diameters of 22, 36 and 75 mm respectively and a constant length-diameter ratio of 0.5. The test results show that the rock dynamic strength increases in form of power with the increase of strain rate and presents strong strain rate dependence. The bigger the specimen size is, the more notable the sensitivity of rock dynamic strength dependence to strain rate is, and the smaller discreteness of the obtained rock dynamic strength is. It is shown that the rock dynamic strength increases with the increase of specimen size under the same strain rate condition which is opposite to the size effect under static loading condition. In addition, the size effect of rock dynamic strength become weaker with the decrease of strain rate. This implies that there has a critical strain rate where the size effect will disappear completely. The static size effect takes the dominant position under the condition that the strain rate is below the critical strain-rate, while the dynamic size effect takes the dominant position under when the strain rate is above the critical strain rate.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2008年第3期526-533,共8页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金重大项目(50490274)
国家自然科学基金资助项目(10472134)
关键词
岩石力学
岩石冲击动力学
尺寸效应
岩石动态强度
应变率灵敏性
SHPB试验
rock mechanics
rock impact dynamics
size effect
dynamic strength of rock
strain rate sensitivity
split Hopkinson pressure bars（SHPB） test
