硬脆性岩石时效强度理论研究

Research on the time-dependent strength criterion of brittle hard rock

随着大型水利水电项目相继竣工投入运行,岩体工程的时效安全性问题成为岩土工作者关心的热点问题。论文以大理岩为例,对硬脆性岩石进行系统的室内力学试验,建立可以描述硬脆性岩石强度时效性的时效强度理论模型。通过单轴、常规三轴压缩试验,研究大理岩的力学特性、破坏模式以及围压的影响,得到大理岩随围压增大出现的脆延转换特性;通过循环加卸载试验,建立大理岩力学参数随塑性内变量的函数表达式,并结合恒载试验得到的大理岩力学参数随时间的变化规律建立大理岩塑性内变量的时效表达式,和时效强度理论模型。结果表明,随时间增长,大理岩的力学参数呈现非线性劣化趋势,并在两周后逐渐趋于稳定,研究成果对岩体工程长期稳定性分析具有重要的理论价值和指导意义。

As the large-scale water conservancy and hydropower projects was completed and put into operation,the long-term safety of rock mass engineering has become a hot issue for geotechnical researchers. In this study,systematic mechanical tests of marble were carried out,and a theoretical model for the time dependent strength was established. The mechanical properties,the failure mechanisms and the confining pressure effect of marble were studied through the uniaxial and conventional triaxial compression tests and the brittle-ductile conversion with the increasing confining pressure was concluded. The variations of mechanical parameters of marble under different plastic degrees were established through the cyclic loading and unloading tests. The variations of mechanical parameters with the time,the expressions of the aging plastic internal variable and the theoretical model of time-dependent strength of marble were established with the results of static fatigue tests. The mechanical parameters of marble degrade nonlinearly with time increasing and keep constant after two weeks.