大理岩硬性结构面剪切蠕变及粗糙度效应研究

 针对锦屏二级水电站地下洞室富含节理的实际情况，利用双轴蠕变仪对大理岩硬性结构面进行剪切蠕变试验。通过对大理岩硬性结构面表面的量测，采用平均粗糙角描述大理岩硬性结构面表面粗糙度情况；分析不同粗糙度情况下岩样剪切位移与时间的变化规律。结果表明，粗糙角大的岩样瞬时变形要小于粗糙角小的岩样。此外，试验在较低的应力水平下，岩样蠕变变形表现为衰减蠕变和稳态蠕变，但当剪应力水平达到某一应力水平时，岩样在极短时间内迅速破坏，未出现加速破坏阶段，因此，利用大理岩剪切蠕变试验数据对标准线性体剪切蠕变模型进行辩识，得出各岩样的剪切蠕变模型参数，通过由模型参数得出的拟合曲线与试验曲线比较知采用标准线性体模型是合理的。最后分析各大理岩岩样的平均粗糙角与剪切蠕变模型参数的变化规律。

STUDY ON SHEAR CREEP AND ROUGHNESS EFFECT ON HARD DISCONTINUITIES OF MARBLE

The rock masses of underground cavern of Jinping II Hydropower Station are enriched in abundant joints. A shear creep experimental program is carried out on hard discontinuities of marble mass using double-axis creep apparatus. Surface of hard discontinuities of marble masses is measured，and roughness of the surface is described by average roughness angle. The variation law of shear displacement of marble with the time is analyzed under different roughness. Test results show that instantaneous deformation of rock sample with large roughness angle is less than that of rock sample with small roughness angle rock sample. In addition，decay and steady creep occur when stress level is relatively low，however，when shear stress level reaches a certain level，rock specimen fails rapidly within a short period of time，and acceleration creep doesnt occur in the process of shear rheology experiment. Consequently，a standard linear shear creep model of marble is identified by shear creep experimental data，and model parameters of marble specimen are gained. The comparison between fitting curve and test curve shows that the standard linear shear creep model is reasonable. Finally，the variation law of average roughness angle of marble specimen and shear creep model parameters is analyzed.