摘要
基于不同温度及应力状态下的蠕变特性试验,结合三维声发射实时监测信息,开展北山花岗岩的蠕变变形特性以及加载条件(温度、围压和应力状态)对其蠕变破坏过程的影响研究。试验结果表明,北山花岗岩的蠕变破坏包括初始蠕变阶段(瞬态蠕变)、稳定蠕变阶段和加速蠕变阶段3个阶段,在加速蠕变过程中裂纹迅速扩展和积聚是导致岩石最终破坏的主要原因。蠕变试验过程中,声发射累计数和岩石蠕变体积应变的演化趋势整体上具有一致性,但声发射信号对岩石变形破坏的敏感性更强。对试验数据综合对比分析显示,花岗岩蠕变破坏变形受围压的影响显著,围压越高,岩石蠕变破坏前所能承受的变形越大。温度和应力水平对蠕变破坏变形影响并不明显,但可以对蠕变速率造成影响,进而改变岩石的蠕变破坏时间。根据试验结果,在围压2,10,30 MPa条件下,北山花岗岩的蠕变破坏轴向应变平均值分别为0.34%,0.54%和0.71%。
The creeping behavior of the granite from Beishan was experimentally studied through a series of creeping tests under different temperatures and stress conditions with the acoustic emission(AE) monitoring.Attention was specially paid on the influence of temperature and stress level on the creeping behavior and cracking process. The experimental data revealed that the creeping process was divided into three stages : the transient, the steady and the accelerated stages. The rock failure was essentially related to the intensive accumulation and coalescence of microcracks during the accelerated stage of creeping. The same tendency between the AE cumulative counts and the volumetric creeping strain was observed. The variation of recorded AE events was found to be more sensitive to the occurrence of rock failure than to the volumetric deformation. Under same confining pressure, the increase of the temperature and stress level had quite limited effect on the total deformation before rock failure, but the cracking process was accelerated leading to the time to failure being reduced. The granite from Beishan failed at the similar values of axial strain under the same confining pressure and failed at the strain about 0.34%, 0.54% and 0.71% under the confining pressures of 2, 10 and 30 MPa respectively.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2015年第6期1228-1235,共8页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(11202069
51374148)
关键词
岩石力学
北山花岗岩
蠕变
裂纹扩展
温度
围压
应力比
rock mechanics
Beishan granite
creep
cracking process
temperature
confining pressure
stress ratio
