深埋大理岩强度参数变化规律的综合试验研究

 深部岩体强度参数的研究相当复杂，与研究尺度、应力状态、应力路径都有关系。以锦屏二级水电站深埋引水隧洞T2b大理岩为研究对象，开展室内标准尺寸岩块岩样、中等尺寸岩石岩样和大尺寸岩体岩样在低–中、中–高、高–极高应力水平下的三轴加、卸载试验，探讨深部岩体强度参数的应力水平效应、应力路径效应和尺寸效应。取得以下成果：(1) 获得室内标准尺寸、中等尺寸和大尺寸大理岩岩样在加、卸载应力路径下低–中、中–高、高–极高应力水平下的10组强度参数；(2) 大理岩抗剪强度参数随应力水平的变化规律基本相同：随着应力水平的提高， 值逐渐减小、c值逐渐增大，但是，不同尺寸和不同应力路径下， 值和c值随围压应力水平的变化幅度并不相同；(3) 相对加载条件，卸载路径下岩体强度参数 值增加，c值减小；(4) 在 50 mm×100 mm至500 mm×500 mm×1 000 mm尺度范围内，大理岩强度参数 值的尺寸效应不明显，而c值的尺寸效应显著。

Experimental study of strength parameters and their variation characteristics of deep marbles

The study on the strength parameters of deep rock mass is complicated and difficult. The strength parameters have close relationships with the sample sizes，stress states and loading paths. A series of triaxial tests are carried out to study the strength parameters and their variations characteristics of T2b marbles from the deeply located intake tunnel of Jinping II Hydropower Station，including the loading and unloading triaxial tests of different size samples in laboratory and in situ with low-middle，middle-high and high-very high confining stresses. Following results can be noted. Firstly，test results of ten sets of different kinds of mentioned triaxial tests on the strength parameters are listed in the paper as to show the effects of confining stress magnitude，stress loading and unloading path，and sample size on strength characteristics. Secondly，the variation characteristics of the strength parameters of T2b marbles show a consistent variation tendency when the confining stress magnitude changed：the value of decreases and the value of c increases with increase of confining stress magnitude，but the ranges of variation of the and c values are not in consistency with different loading paths and different sample sizes. Thirdly，compared to loading condition，the unloading path will lead to a higher value of the strength parameter and a lower value of parameter c. At last，The size effect of the strength parameter of the marbles in the scale from 50 mm×100 mm to 500 mm×500 mm×1 000 mm is not obvious，but the size effect of the strength parameter c is significant.